DESC:Technical Field
[0001] The present invention relates to a field of civil engineering, and, more particularly, to excavation by construction of cast concrete structures, such as diaphragm walls in the earth.
Background
[0002] Diaphragm walls are generally constructed during excavation to form a water-blocking and earth-retaining barrier surrounding underground structures such as tunnels, basements, or roadway cuttings. In general, a diaphragm wall is a reinforced concrete wall which may be cast in-situ in the earth. Typically, to construct a diaphragm wall, a trench may be dug to a desired size. After the trench has been dug, a concrete mix may be poured into the trench to cast the diaphragm wall.
[0003] Once the diaphragm wall is casted, earth portion located on one side of the casted diaphragm wall may be excavated up to a certain depth to reveal a cantilevered diaphragm wall structure. Such cantilevered diaphragm wall structure may be subjected to several lateral pressures, such as earth pressure, hydrostatic pressure, etc., on one side. Such lateral pressures may impart a bending moment to the cantilevered diaphragm wall structure, thereby subjecting one side of the diaphragm wall structure to tensile stresses. If the tensile stresses may be of sufficient magnitude, fractures may occur in such cantilevered diaphragm wall structure. This may reduce the strength of the cantilevered diaphragm wall structure which may even cause the cantilevered diaphragm wall structure to fail.
[0004] To maintain the integrity and stability of the cantilevered diaphragm wall structure, one commonly known solution is simply to embed the diaphragm wall structure deep below into the ground. However, such deep embedment of the cantilevered diaphragm wall structure requires larger, more expensive equipment, increased labor, and increased volume of concrete, resulting in a substantial increase in the costs of construction of the diaphragm walls.
Summary of the Invention
[0005] The present disclosure relates to a method for preparing a ground for excavation up to an excavation depth. The method includes forming a first trench and a second trench spaced apart from the first trench at least partly around the ground. Further, the method includes forming at least one third trench between and interconnecting the first trench and the second trench such that the at least one third trench defines a trench depth below the excavation depth. Also, the method includes pouring a first volume of concrete mix into the at least third trench such that the concrete mix attains a height equal to or less than the excavation depth from the trench depth. In addition, the method includes pouring a second volume of concrete mix into the first trench and a third volume of concrete mix into the second trench, such that each of the second volume of concrete mix and the third volume of concrete mix reaches below or at least up to a level of the ground. Furthermore, the method includes allowing each of the first volume of concrete mix, second volume of concrete mix, and the third volume of concrete mix to settle and stabilize. In that manner, the second volume of concrete mix form a first diaphragm wall and the third volume of concrete mix form a second diaphragm wall, with the first volume of concrete mix forming an intermediate support structure to support the first diaphragm wall and the second diaphragm wall.
Brief Description of Drawings
[0006] FIGS. 1 to 8 illustrate a method for preparing a ground for excavation, in accordance with an embodiment of the present disclosure; and
[0007] FIG. 9 is sectional view of a desired site formed after excavating the ground prepared by the method discussed in FIGS. 1 to 8, in accordance with an embodiment of the present disclosure.
Detailed Description
[0008] Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
[0009] Referring to FIGS. 1 to 8, an exemplary method 100 for preparing a ground 10 for excavation is disclosed. Once the ground 10 is prepared according to the method 100, the ground 10 may be excavated up to a desired excavation depth “D” to form a desired site “S” (see FIG. 9) which may be used as a foundation for underground structures such as tunnels, car-parking basements, etc.
[0010] Firstly, at step 102, an outline 14 of the ground 10 to be prepared for excavation may be defined. The use of the term “defined” in the context of describing the step 102 may refer to demarcating, delimiting, outlining, etc. a surface of the earth 12 so as to lay-out the outline 14 of the ground 10 to be prepared for excavation. The outline 14 may fix a length “L” and a width “W” of the ground 10 to be prepared, and thus it encompasses an area 16 of the ground 10 to be excavated.
[0011] Next, at step 104, a first trench 18 and a second trench 20 are formed in the earth 12. The first trench 18 is formed for casting a first diaphragm wall 60 and the second trench is formed for casting a second diaphragm wall 62 (see FIGS. 8 and 9). The first trench 18 and the second trench 20 may be formed by using any suitable excavation device, such as any known shovel, digger, scoop, trowel, dredge, etc. which may be operated mechanically, pneumatically, and/or hydraulically.
[0012] The first trench 18 and the second trench 20 are located spaced apart along the width “W” of the ground 10. The first trench 18 and the second trench 20 are formed at least partly around the ground 10. In the present embodiment, the first trench 18 and the second trench 20 are formed at two opposite sides of the outline 14 of the ground 10. Also, the first trench 18 and the second trench 20 have lengths “L1” and “L2”, respectively, parallel to the length “L” of the ground 10. In the present embodiment, the length “L1” of the first trench 18 and the length “L2” of the second trench 20 may be equal to the length “L” of the ground 10, although in actual practice or application lengths “L1” and “L2” may differ from each other. Furthermore, the first trench 18 may be formed by excavating the earth 12 to a first depth “D1” and the second trench 20 may be formed by excavating the earth 12 to a second depth “D2” (see FIG. 4). In the present embodiment, the first depth “D1” of the first trench 18 is equal to the second depth “D2” of the second trench 20, although in actual practice or application depths “D1” and “D2” may differ from each other.
[0013] Subsequent to the formation of the first trench 18 and the second trench 20, the method 100 proceeds to step 106, as shown in FIG. 3. At step 106, at least one third trench 22 is formed in the ground 10. In the present embodiment, three third trenches 22 are formed between the first trench 18 and the second trench 20. Each third trench 22 is formed for casting an intermediate support structure 70. Similar to the first trench 18 and the second trench 20, each third trench 22 may be formed by using any suitable excavation device, such as any known shovel, digger, scoop, trowel, dredge, etc. which may be operated mechanically, pneumatically, and/or hydraulically.
[0014] Each third trench 22 may be formed by excavating the earth 12 up to a trench depth “D3” (see FIG. 4) below the excavation depth “D”. In the present embodiment, the trench depth “D3” attained by at least one third trench 22 is equal to the first depth “D1” and the second depth “D2” attained by the first trench 18 and the second trench 20, respectively. In another embodiment, the trench depth “D3” attained by the at least one third trench 22 may be lower than the first depth “D1” and the second depth “D2” attained by the first trench 18 and the second trench 20, respectively. In yet another embodiment, the first depth “D1” and the second depth “D2” attained by the first trench 18 and the second trench 20, respectively, may be lower than the trench depth “D3” attained by the at least one third trench 22.
[0015] Continuing with FIG. 3, each third trench 22 extends transversely along the width “W” of the ground 10. Each third trench 22 includes a first end 30 and a second end 32 opposite to the first end 30. Also, each third trench 22 extends between the first trench 18 and the second trench 20 such that each third trench 22 is connected to the first trench 18 at the first end 30 and is connected to the second trench 20 at the second end 32. In that manner, each third trench 22 interconnects the first trench 18 and the second trench 20. In the present embodiment, the third trenches 22 are located spaced apart along the length “L” of the ground 10. In some other embodiments, more or less than three third trenches 22 may be formed between the first trench 18 and the second trench 20.
[0016] Once the first trench 18, the second trench 20, and the at least one third trench 22 are formed, the method 100 may proceed to step 108, as shown in FIG. 5. At step 108, reinforcement 38, such as steel/iron cage structures, may be positioned within the first trench 18, the second trench 20, and the third trench 22. In an exemplary embodiment, as shown in FIG. 5, the reinforcement 38 may be formed of a first reinforcement 40, a second reinforcement 42, and at least one third reinforcement 44, wherein the first reinforcement 40 may be positioned within the first trench 18, the second reinforcement 42 may be positioned within the second trench 20, and the third reinforcement 44 may be positioned within each third trench 22. In the present embodiment, the first reinforcement 40, the second reinforcement 42, and the third reinforcement 44, are coupled to each other, for e.g., via welding, before performing the step 108. However, it may be contemplated that the first reinforcement 40, the second reinforcement 42, and the third reinforcement 44, may be positioned independently within the corresponding first trench 18, the second trench 20, and the third trench 22, respectively.
[0017] The first reinforcement 40 has a first height “H1” required for casting the first diaphragm wall 60, and the second reinforcement 42 has a second height “H2” required for casting the second diaphragm wall 62. Also, the third reinforcement 44 has a third height “H3” required for casting the intermediate support structure 70. In an embodiment, the first height “H1” of the first reinforcement 40 may be equal to the second height “H2” of the second reinforcement 42, and the third height “H3” of the third reinforcement 44 may be less than the first height “H1” and the second height “H2” of the corresponding first reinforcement 40 and the second reinforcement 42, respectively.
[0018] Subsequent to positioning the first reinforcement 40, the second reinforcement 42, and the third reinforcement 44, the method 100 proceeds to step 110, as shown in FIG. 6. At step 110, a first volume “V1” of concrete mix is poured into the at least one third trench 22 to cast the at least one intermediate support structure 70 (as shown in FIGS. 8 and 9). The term “poured” as used in the context of step 110 may refer to any operation whereby the first volume “V1” of concrete mix is added into the third trench 22. The first volume “V1” of concrete mix is poured to partially fill the third trench 22 up to a height “H4” from the trench depth “D3”. In the present embodiment, the attained height “H4” is less than the desired excavation depth “D” (i.e., lower than a desired level of the site “S”). In another embodiment, the attained height “H4” may be equal to the excavation depth “D” (i.e., equal to a desired level of the site “S”).
[0019] The step 110 may be performed by using any suitable filling devices, such as hoppers 80 and tremie pipes 82 (as shown in FIG. 6) known in the art. In some embodiments, before performing the step 110, shutters (not shown) may be positioned at the first end 30 and the second end 32 of the third trench 22 to prevent a flow of the poured concrete mix into the first trench 18 and the second trench 20.
[0020] Once the first volume “V1” of the concrete mix is poured into the third trench 22, the method 100 proceeds to step 112. At step 112, the first volume “V1” of the concrete mix is allowed to settle and stabilize within the at least one third trench 22 to form the intermediate support structure 70. To perform step 112, the first volume “V1” of the concrete mix is left undisturbed within the third trench 22 for a predefined time to allow the first volume “V1” of the concrete mix to gain compressive strength. For example, the first volume “V1” of the concrete mix may be left undisturbed for the predefined time of about a week or two weeks.
[0021] After the first volume “V1” of the concrete mix gets stabilized and gains appropriate strength, the method proceeds to step 114, as shown in FIG. 7. At step 114, a second volume “V2” of concrete mix is poured within the first trench 18 to cast the first diaphragm wall 60, and a third volume “V3” of concrete mix is poured within the second trench 20 to cast the second diaphragm wall 62. The second volume “V2” of concrete mix is poured into the first trench 18 such that the second volume “V2” of concrete mix reaches at least up to a level “G” of the ground 10. In other embodiments, the second volume “V2” of concrete mix may be poured into the first trench 18 such that the second volume “V2” of concrete mix may reach below the level “G” of the ground 10. Similarly, the third volume “V3” of concrete mix is poured into the second trench 20 such that the third volume “V3” of concrete mix reaches at least up to the level “G” of the ground 10. In other embodiments, the third volume “V3” of concrete mix may be poured into the second trench 20 such that the third volume “V3” of concrete mix may reach below the level “G” of the ground 10.
[0022] Once the second volume “V2” of concrete mix and the third volume “V3” of concrete mix are poured into the corresponding first trench 18 and the second trench 20, respectively, the method 100 proceeds to step 116. At step 116, the second volume “V2” of concrete mix and the third volume “V3” of concrete mix are allowed to settle and stabilize within their corresponding first trench 18 and the second trench 20, respectively, to form the first diaphragm wall 60 and the second diaphragm wall 62. To perform step 116, the second volume “V2” of concrete mix and the third volume “V3” of concrete mix are left undisturbed within the first trench 18 and the second trench 20, respectively, for a predefined time. For example, the first volume “V1” of the concrete mix may be left undisturbed for the predefined time of about a week or two weeks. Once set and stabilized, the first volume “V1” of concrete mix, the second volume “V2” of concrete mix, and the third volume “V3” of concrete mix may be bonded to each other to form a rigid concrete structure (as shown in FIG. 8) capable of withstanding the various lateral pressures and/or forces of the earth 12.
[0023] In the present embodiment, the step 110 (i.e., pouring the first volume “V1” of concrete mix into the third trench 22) and the step 112 (i.e., allowing the first volume “V1” of concrete mix to set within the third trench 22) is performed before the step 114 (i.e., pouring the second volume “V2” and the third volume “V3” into the first trench 18 and the second trench 20, respectively) and the step 116 (i.e., allowing the second volume “V2” of concrete mix and the third volume “V3” of concrete mix to set within their corresponding first trench 18 and the second trench 20, respectively). However, in another embodiment, it may be contemplated that the step 114 and the step 116 may be performed before the step 110 and the step 112. In yet another embodiment, it may be contemplated that the step 114 and the step 116 may be performed simultaneously with the step 110 and the step 112.
[0024] Also, in the present embodiment, the first reinforcement 40, the second reinforcement 42, and the third reinforcement 44, are casted in-place correspondingly within the first trench 18, the second trench 20, and the third trench 22 to form the first diaphragm wall 60, the second diaphragm wall 62, and the intermediate support structure 70. However, in some embodiments, it may be contemplated that the first reinforcement 40, the second reinforcement 42, and the third reinforcement 44 may be pre-casted or partially pre-casted before being positioned correspondingly within the first trench 18, the second trench 20, and the third trench 22.
Industrial Applicability
[0025] Generally, a ground for excavation is prepared by embedding diaphragm walls to a conventional depth deep below a desired excavation depth. Such deep embedment of the diaphragm walls is generally required to enable the diaphragm walls to withstand several lateral pressures and/or forces imparted on the diaphragm walls after an excavation work. However, such deep embedment of diaphragm walls may result in a substantial increase in the costs of construction of the diaphragm walls, which may reflect in the overall cost of a construction project.
[0026] The present disclosure provides the method 100 for preparing the ground 10 between the first diaphragm wall 60 and the second diaphragm wall 62 for excavation. Each of the first diaphragm wall 60 and the second diaphragm wall 62 are embedded up to the depths “D1” and “D2”, respectively, proximal to the desired excavation depth “D” (as shown in FIG. 9) without compromising the strength and stability of the first diaphragm wall 60 and the second diaphragm wall 62. The depths “D1” and “D2” are lesser as compared to the conventional depth. The reduction in the depths “D1” and “D2” of the first diaphragm wall 60 and the second diaphragm wall 62, respectively, is attained by casting at least one intermediate support structure 70 between the first diaphragm wall 60 and the second diaphragm wall 62. The at least one intermediate support structure 70 interconnects the first diaphragm wall 60 and the second diaphragm wall 62, thereby letting the lateral pressures and/or forces imparted on the first diaphragm wall 60 to act as a reaction to the lateral pressures and/or forces imparted on the second diaphragm wall 62, and/or vice versa. Accordingly, the overall construction costs may get significantly reduced.
[0027] It will be apparent to those skilled in the art that various modifications and variations can be made to the method/process of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the method/process disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalent.
,CLAIMS:1. A method for preparing a ground for excavation up to an excavation depth, the method comprising:
forming a first trench and a second trench spaced apart from the first trench at least partly around the ground;
forming at least one third trench between and interconnecting the first trench and the second trench such that the at least one third trench defines a trench depth below the excavation depth;
pouring a first volume of concrete mix into the at least third trench such that the concrete mix attains a height equal to or less than the excavation depth from the trench depth;
pouring a second volume of concrete mix into the first trench and a third volume of concrete mix into the second trench, such that each of the second volume of concrete mix and the third volume of concrete mix reaches below or at least up to a level of the ground;
allowing each of the first volume of concrete mix, second volume of concrete mix, and the third volume of concrete mix to settle and stabilize, such that the second volume of concrete mix form a first diaphragm wall and the third volume of concrete mix form a second diaphragm wall, with the first volume of concrete mix forming an intermediate support structure to support the first diaphragm wall and the second diaphragm wall.
2. The method as claimed in claim 1, further comprising allowing the first volume of concrete mix to settle and stabilize within the at least one third trench prior to pouring the second volume of concrete mix into the first trench and the third volume of concrete mix into the second trench.
3. The method as claimed in claim 1, wherein a depth attained by each of the first trench and the second trench is lower than the trench depth of the at least one third trench.
4. The method as claimed in claim 1, wherein the trench depth of the at least one third trench is lower than a depth attained by each of the first trench and the second trench.
5. The method as claimed in claim 1, wherein the trench depth of the at least one third trench is equal to a depth attained by each of the first trench and the second trench.
6. The method as claimed in claim 1, further comprising positioning shutters at ends of the at least one third trench to prevent a flow of the concrete mix into the first trench and the second trench.
7. The method as claimed in claim 1, further comprising positioning a first reinforcement in the first trench, a second reinforcement in the second trench, and at least one third reinforcement in the at least one third trench.
8. The method as claimed in claim 7, wherein the first reinforcement attains a first height, the second reinforcement attains a second height, and the third reinforcement attains a third height,
wherein the first height of the first reinforcement being equal to the second height of the second reinforcement, and
wherein the third height of the third reinforcement being less than the first height and the second height of the corresponding first reinforcement and the second reinforcement.