Description:FIELD OF INVENTION :

The present invention relates to the testing setup/equipment, which evaluates the consistency of modified soil using conditioning agents in the earth pressure balancing tunnel boring machine.

PRIOR ART :

Earth Pressure Balance Machine generally referred as EPB – Tunnel Boring Machine

Tunnel Boring Machines generally referred as TBM are highly specialized machines that bore through the earth to construct various infrastructures, from super-highways to water-overflow systems. Among the various types of TBMs, Earth Pressure Balance Machines (EPB) are specially designed TBM for operation in soft ground conditions containing:

• Water under pressure
• Loose sedimentary deposits
• Sands, gravels, silts, clays
• Formations with large boulders
• High water table

The standout feature of EPB TBMs is that they use the excavated soil as a support medium. The rotating cutter head, equipped with cutting tools, pushes into the tunnel face and excavates the soil, which enters the excavation chamber through openings. Here, it mixes with the appropriate conditioning agents already present. Mixing arms on the cutting wheel and bulkhead, mix the paste until it has the required texture. The bulkhead transfers the pressure of the thrust cylinders to the pliable soil paste. The EPB TBM turns the excavated material into a soil paste which can be used as a malleable, plastic support medium. This makes it possible to balance the pressure conditions at the tunnel face, avoid uncontrolled soil inflow into the machine and create the right conditions for rapid tunnelling with a minimum settlement.

Soil Conditioning Additives

EPBM tunnelling generally requires additives which make it possible to cut, support and transport the soil with economical boring parameters. Soil conditioning can be achieved by adding foam and/or additives. The selection of the foam type and the additive depends mainly on the soil type in situ but also on the characteristics of the TBM. Types of additives include special anti-clogging agents to avoid clogging problems, anti-abrasion additives for the cutter head and its tools, and the extraction screw conveyor. Bentonite and/or fine particles can be added to soils without fines. The soil with high clay content can be modified by adding anti-clay agents with foaming additives. Apart from this, other additives are also being used to avoid segregation and reduce the permeability of the soil. As per the EFNARC, the foam additives are intended to achieve one or more effects such as Maintenance of pressure, fluidising effect for the soil, creation of a homogeneous soil paste, permeability reduction, lowering of torque, reduction of soil stickiness, and reduction of abrasion. In some cases, polymers can be added to improve foam stability or adjust the consistency of the soil passing through the working chamber and screw conveyor. A typical example might be in wet, sandy soils with little cohesion. By correctly choosing these products and their composition to match the requirements of the encountered soil and groundwater conditions, they can:

• Reduce the stickiness of plastic clays (which can lead to muck conveying system blockage) by TBM.
• Lower the angle of internal friction and abrasiveness of the soil slurry (in order to reduce power for soil extraction and conveyance and also the wear costs)
• Create plastic deformation behaviour (providing an even and controlled supporting pressure increases the stability of the face and reduces segregation and the consequent risk of settlement)
• Adjust the soil consistency to enable tunnelling by EPBM.
• Reduce soil permeability to minimise water ingress.

DRAWINGS OF THE INVENTION :

Fig. 1 details the units A-D with all components marked therein of the invention.

Part no. Part names
A Unit A height adjustable stand
1 Column
2 Carriage
3 Handwheel
4 Base
5 Motor connection rod
B Unit B Electromechanical setup
6 Motor
7 Torque Transducer
8 Disc
9 Controller
C Unit C Pressure development frame
10 Top Plate
11 Base Plate
12 Reaction plate
13 Hydraulic Jack
14 Hydraulic Pump
15 Hydraulic Hose
16 Platen
17 Cylindrical container
18 test sample
19 Column Rods
D Unit D Data Logger

Fig. 2 Picture of The Test Setup of Tangential Adhesion

DESCRIPTION OF INVENTION :

In order to choose the correct product (Foam type), the proportion and the effectiveness of foam, it is necessary to test three important parameters: foam density, foam stability and plasticising effect. Experience in operating these tests could be improved, especially in finding the plasticising effects. The current invention states a testing setup to determine the plasticising effect on the soil by adding foam/polymer additives. This test setup consists of a tank made of MS steel with dimensions of 250mm diameter and 300mm height and a spindle with a circular disk of diameter 200mm. To rotate the spindle inside the tank filled with modified soil, a high-capacity motor shall be attached to rotate at 120 RPM. The motor can measure torque up to 90 N.m. The test setup also consists of a pressuring system that can be adjusted to simulate the field condition.

The test setup can measure the soil’s consistency by calculating the torque required to rotate a spindle with a circular Disk at a specific RPM (90 rpm). The test shall be performed by applying various confining pressures on the soil, simulating the real field condition.

Working Mechanism:

There are four portions in the system :

Unit A height adjustable stand setup
a. Column 1
b. Carriage 2
c. Handwheel 3
d. Base 4
e. Motor connection rod 5

Unit B Electromechanical setup
a. Motor 6
b. Torque Transducer 7
c. Disc 8
d. Controller 9

Unit C Pressure development frame setup
a. Top Plate 10
b. Base Plate 11
c. Reaction plate 12
d. Hydraulic Jack 13
e. Hydraulic Pump 14
f. Hydraulic Hose 15
g. Platen 16
h. Cylindrical container 17
i. test sample 18
j. Column Rods 19

Unit D Data logger setup

The arrangements of four units A-D are detailed herein in terms of physical and mechanical construction and so also the operational and functional relationship between the components covered in each unit mutually within the unit and also mutually also with other units.

Tangential adhesion tests perform with different types of soil with varying characteristics (grain size and consistency behaviour) to gauge the influence of the conditioning agent on the torque requirement for tunnel boring machine operation. The typical tangential adhesion test starts with the sample preparation (with or without a conditioning agent) based on the required mix proportion (mix proportion of soil, water, and conditioning agent). Then the soil sample is transferred into the cylinder (part 17). After the proper soil placement, the circular disc arrangement (part 8) is placed inside the soil sample to measure the soil adhesive force as well as torque as an output. The height of the electromechanical setup (unit B) and disc (with rod) is used to adjust by revolving handwheel (part 3). A motor rotates this disc with 90 rpm rotational speed (part 6). As an effect, soil resists the rotating disc due to the soil's frictional and adhesive properties (based on various soil types). For example, the motor needs to apply high torque to rotate the disc in case of highly cohesive soil, whereas soft soil requires a lower torque. The tangential adhesion test captures this variation in torque by the motor transducer (part 7). The addition of a conditioning agent alters the resistive force of soil for rotation. Quantifying this decrement in the torque requirement of the motor is the reason for the evolvement of this test setup. Another crucial part of this test setup is the simulation of site conditions through the pressure application procedure.

Tunnel boring machines encounter high horizontal and vertical pressure from surrounding soil for underground excavation work. The present setup is designed to simulate this site condition based on the reaction mechanism (unit C). After the soil placement and accurate positioning of the rotating disc and electromechanical setup, a plate (which is used to attach to the rod; reaction plate part 12) is placed on the soil sample. The position of the reaction plate is fixed with the help of three reaction rods (part 19) from the top plate (part 10). Now the pressure is applied with the help of a hydraulic jack and pressure pump system (parts 13 and 14). The hydraulic jack moves upwards due to the application of pressure from the hydraulic pump. The reaction plate resists the upward movement of the soil sample, and corresponding pressure (100 kPa) is exerted on the soil sample. After the application of pressure, torque is measured with the help of a transducer.

Fig 1 is the schematic view of tangential adhesion test equipment. As shown in Fig 4, the equipment consists of the following four major units.

Unit A – Height adjustable stand
Unit B – Electromechanical setup
Unit C – Pressure development frame
Unit D – Data Logger
In order to perform the tangential adhesion test, the equipment shown in fig 4 consists of four major units involved in this operation. Each unit collaborates synchronously to perform the tangential adhesion test.

The function of Unit A in Fig 1 is to carry unit B, move unit B up and down at user-defined heights, and hold unit B stably at any position along the height of column 1. Column 1 in unit A must be stiff enough to support the electromechanical setup of unit B. while unit B travel along the height of column 1, it should be smooth, steady, and without vibration. During the operation, non-operation, and stop states of Unit A and Unit B, Unit B must be held firmly in place without sagging due to weight and gravity.

Unit A, shown in Fig 1, consists of column 1, which carries the load and holds carriage 2 at the desired height. Column 1 is attached to base 4, which keeps the whole Unit A stand stable on the floor. Base 4 can be freely placed on the floor or fixed to the ground. Carriage 2 is mounted on the column 1 rack and pinion mechanism, which allows smooth carriage movement along column 1. Carriage 2 consists of a Handwheel 3 to manually move up and down carriage 2 to the desired height along column 1.

The function of Unit B, as shown in fig 1, is to spin disc 8 at a constant rate of speed. Unit B consists of motor 6, torque transducer 7, disc 8, and controller 9. Disc 8 is connected to motor 9 and rotates at constant speed if the torque required is varying or fixed. The torque required to spin disc 8 is measured using the torque transducer 7. Controller 10, electrically connected to motor 6, controls the electrical power supplied to motor 6 to operate the motor at a set speed.

The function of Unit C, as shown in fig 1, is to apply the test pressure to sample 18 placed in the cylindrical container 17. Unit C consists of Top Plate 10, Base Plate 11, Reaction plate 12, Hydraulic Jack 13, Hydraulic Pump 14, Hydraulic Hose 15, Platen 16, cylindrical container 17, test sample 18, and column rods 19. The top plate 10 and Base plate 11 are spaced enough to accommodate the cylindrical container 17. The top plate 10 and Base plate 11 are connected mechanically with the help of column rods 19. Test sample 18 will be inside the container. The reaction plate 12 will be placed over test sample 18 and connected to the top plate 10. The required pressure will be applied to the test sample 18 by pumping the hydraulic jack 13 by the hydraulic pump 14.

The function of unit D, as shown in fig 1, is to log the data from the torque transducer 7

As detailed above, it is obvious that the system disclosed for tangential adhesion test is novel and process of identifying and measuring the plasticising effect is also novel, hitherto unknown in prior art.

The novel features of the invention are that it is tangential adhesion test equipment comprising:

a. A height-adjustable stand (Unit A) consisting of a column (1) for carrying the load, a carriage (2) mounted on the column (1) rack and pinion mechanism, a hand wheel (3) for manual movement of the carriage (2) up and down along the column (1), and a base (4) for keeping the stand stable on a floor.
b. An electromechanical setup (Unit B) consisting of a motor (6), a torque transducer (7), a disc (8) connected to the motor (6) for spinning at a constant speed, and a controller (9) for controlling the electrical power supplied to the motor (6).
c. A pressure development frame (Unit C) consisting of a top plate (10), a base plate (11), a reaction plate (12), a hydraulic jack (13), a hydraulic pump (14), a hydraulic hose (15), a platen (16), a cylindrical container (17) for accommodating a test sample (18), and column rods (19) for mechanically connecting the top plate (10) and base plate (11); and
d. A data logger (Unit D) for logging data from the torque transducer (7).
In another aspect column (1) of the equipment is stiff enough to support the electromechanical setup (Unit B), and the movement of the carriage (2) along column (1) is smooth, steady, and without vibration.

In another aspect of the invention, the torque transducer (7) measures the torque required to spin the disc (8) at a constant speed.

In another aspect of the invention, the pressure development frame (Unit C) applies the required pressure to the test sample (18) by pumping the hydraulic jack (13) using the hydraulic pump (14).

In another aspect of the invention beyond the system it also covers method of performing a tangential adhesion test using the tangential adhesion test equipment as detailed herein.

a. Adjust the height of the electromechanical setup (Unit B) using the adjustable height stand (Unit A).
b. spinning the disc (8) at a constant speed using the motor (6).
c. measuring the torque required to spin the disc (8) at the constant speed using the torque transducer (7).
d. placing a test sample (18) inside the cylindrical container (17) of the pressure development frame (Unit C).
e. applying a required pressure to the test sample (18) using the pressure development frame (Unit C); and
f. logging data from the torque transducer (7) using the data logger (Unit D).

All of which disclose combinedly effectively work to detect the plasticising effect of the soil robustly but without much effort or cost. The invention disclosed herein may be variable in certain aspects as known to skilled persons in the art and all of such variants are covered within the scope of this invention.
, Claims:WE CLAIM :

1. A testing system for evaluating consistency of sample soil (18) preparation with or without conditioning agents comprising of :

a. a portion C having a top plate (10) and a base plate (11) disposed spaced away from the top plate (10) and a cylindrical soil container (17) disposed therein between the top plate (10) and the bottom plate (11), a reaction plate (12) disposed within the container (17) and attachable to the top plate (10) with plurality of rods (19) and a moveable hydraulic jack (13) extending into and out of cylindrical container,
b. a portion B having a torque transducer (7), operably associated with a controller (9) and a disc (8) fixed to a spindle operable by a motor (6), the said disc (8) disposed into the cylindrical container (17) of portion C, and such that it is beneath the reaction plate (12),
c. a portion A having a moveable carriage (2) mounted on a column (1) fixed on a base (4), and a motor connector rod (5) extending outwardly from the carriage (2) and attached to motor (6) of portion B, and
d. a portion D is a data logger operably associated with the torque transducer (7) of portion B,

the said arrangement characterised in the motor operable rotating disc (8) arranged against the soil’s (18) frictional and adhesive properties and in the reaction plate (12) against which hydraulic pressure is applied with hydraulic jack (13) thereby corresponding pressure exerted to on the soil sample (18) and torque measured with a torque transducer (7) associated with a data logger.
 
2. A process for evaluating consistency of a sample soil preparation with or without conditioning agent with a system as claimed in claim 1.