WO2012101651A1

WO2012101651A1 - Triaxial geocomposite testing apparatus for calibrating pressure transducers

Info

Publication number: WO2012101651A1
Application number: PCT/IN2011/000407
Authority: WO
Inventors: Dasaka Satyanarayana MURTY; Dave Trudeep NITINCHANDRA
Original assignee: Indian Institute Of Technology, Bombay
Priority date: 2011-01-25
Filing date: 2011-06-17
Publication date: 2012-08-02

Abstract

A triaxial geocomposite testing apparatus 100 for simultaneously calibrating multiple pressure transducers 136, 162 are provided. The apparatus 100 includes a base 104 that has an inlet 120, an outlet 122, and a plurality of spaced apart lateral openings 126 formed therein. At least one pressure transducer 136, 162 insertable within the fluid retaining section 106 through a corresponding opening 126 for providing electrical signals during testing. A pedestal 144 is attacheable to the base 104 and includes at least one recess 154 formed on its top surface 148. The at least one recess 154 has a first diameter and includes atleast one earth pressure transducer 162 having a second diameter positionable therein. A holding member 166 is also disposed within the at least one recess 154 for allowing the at least one earth pressure transducer 162 to be tightly retained therein.

Description

TITLE OF THE INVENTION

TRIAXIAL GEOCOMPOSITE TESTING APPARATUS FOR CALIBRATING PRESSURE TRANSDUCERS

FIELD OF THE INVENTION

[0001] The present invention relates to calibration of pressure transducers and more particularly, calibration of pressure transducers within a modified geocomposite triaxial testing apparatus.

DESCRIPTION OF THE BACKGROUND ART

[0002] For construction materials such as rocks, soil, concrete, and the like, it is very important to determine a variety of properties under stress conditions. In Geomechanics art, pressure measuring devices are mostly used for measuring actual stresses acting on such materials during experiments conducted in laboratory and in-situ. Accordingly, it is imperative for such devices that they provide accurate readings or else, properties analyzed for such materials will be questionable. However, due to the fact that these devices are electro-mechanical devices, such devices are bound to give some errors in the readings. This may be attributed to repeated and prolonged use of such devices, usage conditions, etc. Precisely for this reason all kinds of pressure transducers are periodically calibrated by their manufacturers. Amongst various known apparatuses, triaxial cells serve very well for determining properties of the above mentioned geocomposite materials and importantly, for calibrating pressure measuring devices.

[0003] For determining various properties of a geocomposite material, a specimen formed of such material positioned on a pedestal of the triaxial cell. An earth pressure transducer is positioned on top of the pedestal and contacts the bottom of the specimen. Further, for specimens of different sizes, a corresponding earth pressure transducer of a definite rating is used. It is well known that for accommodating transducers of different sizes within pedestals, different sizes of the pedestals are required to be manufactured and used within the triaxial cell. Once the specimen is positioned, the specimen is subjected to vertical and lateral stresses within the triaxial cell. The vertical stress is exerted by a loading ram or a piston on the top of specimen whereas the lateral stress is exerted by a fluid confined within the triaxial cell and subjected to pressure. As a result of this set up and the stresses acting on the geocomposite sample, various properties such as compressive strengths, deformation characteristics, etc., concerning the specimen could be determined.

[0004] Further, for calibrating earth pressure transducers of a particular size, a pedestal corresponding to the size of the transducer is taken and fitted at the base of the triaxial cell. The earth pressure transducer is tightly fitted within a recess formed on a top surface of the pedestal and thereafter, the container is filled with the fluid, for example water, and a series of pressure within the range not exceeding the maximum capacity of the transducer is applied to the fluid. During operation, once the readings from the earth pressure transducers start flowing, a relationship between the applied fluid pressure and the output signal (in the form of microstrain με or microvolt ν) is established. Similar relationships between various fluid pressure and the output signals are established. For calibrating pressure transducer of a different size, the pedestal corresponding to that size is taken and similar relationships are conducted. Investigation of relationships is carried out and a necessary 'calibration factor' is multiplied to the output readings. Preferably, a chart relating the applied pressure and the calibrated earth pressure transducer output is prepared and provided to end user for further use.

[0005] Though such experiments gave satisfactory readings for calibration purposes, however there are various limitations in such triaxial cells. One of the limitations is that at a time only one earth pressure transducer of a particular size could be calibrated within the triaxial cell. Thus, for calibrating another earth pressure transducer of same or different size the whole pedestal needs to be replaced by a matching one. Therefore, having various pedestals to cater different sizes of the earth pressure transducers leads to major cost disadvantage on the part of the end consumers. Another limitation relates to calibrations of plurality of pore pressure transducers which are used for measuring pore pressures within particulate media.

[0006] Thus, there is a need to invent a modified triaxial testing apparatus which can facilitate simultaneous calibration of multiple pressure transducers of same/different sizes.

SUMMARY OF THE INVENTION

[0007] Disclosed herein is a triaxial geocomposite testing apparatus for simultaneously calibrating multiple pressure transducers including a fluid retaining section extending between a top portion and a base having an inlet, an outlet, and a plurality of spaced apart lateral openings formed therein, a fluid having a pressure fillable within the fluid retaining section through the inlet and dischargeable therefrom through the outlet, at least one pressure transducer insertable within the fluid retaining section through a corresponding opening for providing electrical signals during testing, a pedestal attached to the base, the pedestal including at least one recess formed on its top surface and an internally formed first passageway connecting the at least one recess to a side opening of the pedestal, the at least one recess having a first diameter and includes atleast one earth pressure transducer having a second diameter positionable therein, the first diameter being greater than the second diameter, the first passageway having an electric cable disposable therein for electrically connecting the earth pressure transducer to a pressure reading device positioned outside the apparatus, the electric cable extendable outside the testing apparatus through a corresponding opening within the base, and a holding member disposed within the at least one recess for allowing the at least one earth pressure transducer to be tightly retained therein, actuation surface of the at least one earth pressure transducer levelled with a top surface of the holding member.

[0008] In some embodiments, the base includes a plate detachably attached thereto, the plate defined by an outer surface, an inner surface, and a central opening, the plurality of lateral openings extending between the outer surface and the inner surface.

[0009] In some embodiments, a pore pressure transducer is insertable within the fluid retaining section through its corresponding opening formed within the plate, the pore pressure transducer providing pressure signals to the pressure reading device during testing.

[0010] In some embodiments, the at least one recess formed in the pedestal includes at least two earth pressure transducers positionable therein, diameters of both the earth pressure transducers being less than the first diameter, and wherein the holding member tightly retaining both the earth pressure transducers therein.

[0011] According to another aspect of the present invention, A triaxial geocomposite testing apparatus for simultaneously calibrating multiple pressure transducers including a fluid retaining section extending between a top portion and a base having an inlet, an outlet, a fluid having a pressure fillable within the fluid retaining section through the inlet and dischargeable therefrom through the outlet, a plate defined by an outer surface, an inner surface, and a central opening, and being detachably attached to the base, the plate including a plurality of spaced apart lateral openings extending between the outer surface and the inner surface, at least one pressure transducer insertable within the fluid retaining section through the corresponding lateral opening, the atleast one pressure transducer providing pressure signals during testing to a pressure reading device positioned outside the testing apparatus, and a pedestal attached to the base, the pedestal including at least one recess formed on its top surface and an internally formed first passageway connecting the at least one recess to a side opening of the pedestal, the at least one recess having at least one earth pressure transducer tightly positionable therein and the first passageway having an electric cable disposable therein, the electric cable connecting the earth pressure transducer to a pressure reading device positioned outside the apparatus, the electric cable extendable outside the testing apparatus through a corresponding opening within the base.

[0012] In some embodiments, the testing apparatus further includes a second passageway and a third passageway, both the second and the third passageways internally extending between a portion of the pedestal adjacent to the at least one recess and an external surface of the base, and wherein both the second and the third passageways connectable to a corresponding channel outside the apparatus.

[0013] Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0014] It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention. A BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above-mentioned and other features and advantages of the various embodiments of the invention, and the manner of attaining them, will become more apparent and will be better understood by reference to the accompanying drawings, wherein:

[0016] FIG. 1 is an elevational cut sectional view of a triaxial geocomposite testing apparatus according to an embodiment of the present invention;

[0017] FIG. 2 is a top view of a detachable plate and a pedestal of the triaxial geocomposite testing apparatus of FIG. 1 ;

[0018] FIG. 3 is a front elevational view of the detachable plate and the pedestal of FIG. 2;

[0019] FIG. 4 is a perspective elevational view of the pedestal of FIG. 1 according to an embodiment of the present invention; and

[0020] FIG. 5 is another perspective elevational view of the pedestal of FIG. 4 having an earth pressure transducer and a holding member tightly fitted therein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] FIG. 1 shows a triaxial geocomposite testing apparatus 100 according to an embodiment of the present invention. The triaxial testing apparatus 100 includes a top 102, a base 104, and a fluid retaining section 106 extending between the top 102 and the base 104. Preferably, the top 102 of the triaxial testing apparatus 100 has a cylindrical shape however other shapes are also considered to be within the scope of the present invention. The top 102 includes a plurality of openings formed across its thickness along an axis of the triaxial testing apparatus. Through one of the openings, a loading ram 108 is insertable within the fluid retaining section 106 and stably held on top of a geocomposite specimen (not shown) positioned within the triaxial testing apparatus. Another opening provided on the top 102 includes an air-release valve 1 10 for carrying out known functions as and when required. Further, the top 102 also includes a plurality of equally spaced apart slots formed therein so as to allow a corresponding tie-rod 1 12 to pass through the corresponding slot. The fluid retaining section 106, which is preferably made from a thick transparent material, is detachably attached between the top 102 and the base 104. For detachably attaching the fluid retaining section 106, adequate grooving 1 14 (FIG. 2) and sealing members 1 16 are provided within surfaces 1 18 of the top 102 and the base 104, respectively. Such an arrangement securely retains the fluid retaining section 106 between the top 102 and the base 104.

[0022] As seen in FIG. 1, the base 104 is shown to have an inlet 120 formed therein. Through the inlet 120 a fluid (not shown) is introduced within the fluid retaining section 106. Once the fluid is introduced, a pressure applying device (not shown) is inserted within the inlet 120 and pressure of various ranges is applied. The inlet 120 of the base 104 also works as an outlet 122 for discharging the fluid out of the triaxial testing apparatus 100. This may be done by coupling a two-way valve with the inlet 120. However, it must be noted that prior to discharging the fluid, the pressure is released through the same inlet in a manner known to a skilled person. In various embodiments, instead of one inlet 120 there may be two passages formed within the base 104 for the inlet 120 and the outlet 122 and considered to be within the scope of the present invention. Accordingly, through the first inlet a fluid may be introduced within the fluid retaining section 106 and whereas through the second inlet pressure is applied by a compressor via control panel so as to pressurize the fluid within the fluid retaining section 106.

[0023] As shown in FIGS. 1 and 2, the base 104 of the triaxial testing apparatus 100 further includes a detachable plate 124 attached to the base 104 and having a plurality of spaced apart lateral openings 126 formed therein. The detachable plate 124 is defined by an inner surface 128, an outer surface 130, a central opening 132, and is sufficiently thick. Preferably, the detachable plate 124 has an outer diameter of 300mm and an inner diameter of 185 mm. A top surface 134 of the detachable plate 124 has a circular groove 1 14 in which a sealing member such as a rubber O-ring 1 16 is fitted. A similar circular groove having the O-ring fitted therein may also be provided in between the detachable plate 124 and the base 104 for sealing any seepage of fluid and pressure. The plurality of lateral openings 126 is formed at equal or at unequal distance from each other within the detachable plate 124. Each of the openings 126 laterally extends between the outer surface 130 and the inner surface 128 of the detachable plate 124. One or more miniature or large-sized earth or pore pressure transducers 136 may be insertable within the fluid retaining section 106 through a corresponding opening 126 provided within the detachable plate 124.

[0024] Further, the pore pressure transducers 136 are inserted prior to filling of the fluid within the fluid retaining section 106. Transmission wires 138 of the pore pressure transducers 136 are extendable outside the triaxial apparatus through the corresponding opening 126 and are connected to a pressure reading device (not shown) known in the art. When the fluid retaining section 106 is filled with fluid, the pore pressure transducers 136 provide their outputs in the form of microstrain (με) or microvolt (μν) to the pressure reading device. Appropriate sealing provisions are provided at each of the openings 126 through which the transmission wires 138 of the pore pressure transducers 136 are inserted. This is done so as to avoid fluid leakage that may lead into loss of the required fluid pressure. Preferably, brass couplings 140 having seals (not shown) disposed therein may be provided at each of the openings 126 from outside of the triaxial testing apparatus 100 (FIGS. 2 and 3). Further, the detachable plate 124 also has a plurality of holes 142 formed between the top surface 134 and a bottom surface thereof and along an axis of the triaxial testing apparatus. Through these holes 142, the tie-rods 1 12 that are introduced from the top 102 are tightly fixed within the detachable plate 124 in known manner. The tie-rod 112 ensures that the fluid retaining section 106 is tightly held between the top 102 and the base 104 when the testing or calibration operation is conducted.

[0025] It is to be understood that in some embodiments of the present invention, the base 104 of the triaxial testing apparatus 100 does not include the detachable plate 124. In such embodiments, the plurality of spaced apart lateral openings 126 may be formed on the lateral side of the base 104 and in the same manner as formed within the detachable plate 124. This would allow manufacturers of triaxial testing apparatus 100 to save on the additional cost incurred for making the detachable plates 124. All such embodiments are considered to be within the scope of the present invention.

[0026] Further, in FIG. 1 the triaxial testing apparatus 100 also includes a pedestal 144 that is removably attached on a top surface 146 of the base 104. Preferably, the pedestal 144 is positioned in the centre of the base 104. The pedestal 144 is defined by a top surface 148, a bottom surface 150, and a lateral side 152 having sufficient thickness (See FIGS. 4 and 5). Further, the top surface 148 of the pedestal 144 includes at least one recess 154 formed thereon. The pedestal 144 also includes a first passageway 156 internally formed therein and extends between the top surface 148 and the lateral side 152 of the pedestal 144 so as to connect the at least one recess 154 with the lateral side 152. The pedestal 144 also includes a second passageway 158 and a third passageway 160 extending between the top surface 148 and the bottom surface 150 of the pedestal 144. As seen in FIG. 1 , the second and the third passageways 158, 160 also extends through the base 104 of the triaxial testing apparatus l OOand open at a side portion thereof. The second and the third passageways 158, 160 are used for determining the pore pressure and the volume change, respectively, associated with a geocomposite specimen when positioned on the pedestal 144 and subjected to a compression testing within the triaxial testing apparatus 100. As seen in FIGS. 4 and 5, the at least one recess 154 is circular in shape and for the purpose of the specification diameter of the at least one recess 154 will be referred to as the first diameter. Preferably, the first diameter has a value of 40 mm however values greater than or less than 40 mm depending on industry requirements may also be possible. Preferably, the pedestal 144 is circular in shape and formed from a metallic material such as brass. However, other shapes and materials for forming the pedestal 144 are also considered to be within the scope of the present invention. Furthermore, the pedestal 144 may also have more than one recess 154 formed thereon and suitably connected with the same first passageway 156. Additionally in order to connect the other recesses 154 with the lateral side 152 of the pedestal 144, corresponding number of first passages 156 may also be formed therein.

[0027] As seen in FIG. 5, an earth pressure transducer 162 having a predetermined second diameter is positioned within the at least one recess 154. The second diameter of the earth pressure transducer 162 is smaller than the first diameter of the at least one recess 154 so that when the earth pressure transducer 162 positioned within the at least one recess 154, the earth pressure transducer 162 is loosely fitted. Preferably, the earth pressure transducer 162 has a diameter of 6.5 mm corresponding to a pressure range of (0-200) kPa. It is to be understood by a skilled person in the art that a thickness of the at least one recess 154 and the earth pressure transducer 162 is equal. Due to equal thicknesses, an actuation surface 164 (or a top surface) of the earth pressure transducer 162 is levelled with the top surface 148 of the pedestal 144.

[0028] Further, as shown in FIG. 5, a holding member 166 is also disposed within the at least one recess 154 and around the earth pressure transducer 162 to fill the vacant space within the at least one recess 154. The holding member 166 is formed of a metallic material such as brass, aluminium, stainless steel and is preferably circular in shape. Furthermore, the holding member 166 includes at least one slot formed across its thickness that corresponds to the shape of the earth pressure transducer 162 having a diameter of 6.5 mm. The at least one hole is formed in such a manner that the earth pressure transducer 162 is comfortably accommodated within the at least one hole. Such arrangement provides a tight fitting to the earth pressure transducer 162 within the at least one hole and the at least one recess 154. This is imperative for providing correct reading during calibration process. Further, the depth of the at least one slot within the holding member 166 is such that a levelled surface is maintained between the two. As a result, the pedestal 144, the holding member 166 and an actuation surface 164 of the earth pressure transducer 162 is levelled with one another. The levelled surfaces and the tight fitting of the pressure transducer ensure that during calibration, the actuation surface 164 of the earth pressure transducer 162 is acted upon by equal pressure of the fluid. In other embodiments of the present invention, earth pressure transducers 162 having diameters lesser than 40mm may be easily fitted within the at least one recess 154 by the usage of adequate holding members 166. It would be understood that for tightly fitting the earth pressure transducer 162 having diameter of nearly 40 mm within the at least one recess 154, no holding member 166 would be required.

[0029] In some embodiments of the present invention, more than one earth pressure transducers

162 (not shown), for example two, may also be positioned within the at least one recess 154. The diameter of both the earth pressure transducers 162 may be equal or different but is sufficiently less than 40 mm, i.e., lesser than the first diameter of the at least one recess 154. Further, the holding member 166 for fitting both the earth pressure transducers 162 has two slots (not shown) formed therein that corresponds to the shape of the two earth pressure transducers 162. The two slots accommodate both the earth pressure transducers 162 therein so as to provide a tight fitting within the atleast one recess 154. It will be understood that all such embodiments should be construed to be within the scope of the present invention. It will also be appreciated by a skilled person in the art that such arrangements may also be possible within the a plurality or all of the recesses 154 formed on the top surface 146 of the pedestal 144 and construed to be within the scope of the present invention.

[0030] In all of the above referred embodiments of the pedestal 144, an electric cable 168 is positioned within the first passageway 156 to connect the earth pressure transducer 162 with an earth pressure reading device (not shown) that may be disposed outside the triaxial testing apparatus. Transmission wires 138 (not shown) of the earth pressure transducer 162 are connected with the electric cable 168 positioned within the first passageway 156. The electric cable 168 extends outside the triaxial testing apparatus 100 from an opening 170 formed on the lateral side 152 of the pedestal 144 and the corresponding opening 126 formed within the detachable plate 124 (FIG. 1). Preferably, brass coupling 140 having seals (not shown) disposed therein may be disposed at the opening 170 to stop seepage of pressure/fluid. As noted above, both the pore pressure transducers 136 and the earth pressure transducer(s) 162 are connected to separate pressure reading device. However, in several embodiments of the present invention, the earth pressure transducers 162 and the pore pressure transducers 136 may be connected to a single pressure reading device known in the art.

[0031] In light of the foregoing description, a skilled person in the art would appreciate that more than one miniature or large-sized pore pressure transducers 136 and the earth pressure transducers 162 could be easily positioned and calibrated within the triaxial testing apparatus. Further, the problem of replacing pedestals 144 as noticed with the prior art triaxial testing apparatuses is fully eliminated as the pedestals 144 of the present triaxial testing apparatuses have provisions for testing multiple earth pressure transducers 162 at the same time. Thus, a combination of a plurality of pore pressure transducers 136 and the earth pressure transducers 162 may be calibrated simultaneously within the triaxial testing apparatus. It will also be appreciated that in the already existing triaxial testing apparatuses, these benefits could be achieved very easily by replacing the previous pedestal with the present pedestal 144 and the detachable plate 124.

[0032] Once the triaxial testing apparatus in accordance with the various embodiments of the present invention is ready, calibration of the various earth pressure transducer(s) 162 and pore pressure transducer(s) 136 starts. During operation, a relationship between the applied fluid pressure and the output signal in the form of microstrain (με) or microvolt (μν) is established. After investigation of relationships is carried out, a necessary 'calibration factor' is added to the output readings and a chart relating the applied pressure and the calibrated earth pressure transducer 162 output is prepared.

[0033] In the various embodiments of the present invention noted above, all the fluid connections or fluid connectivity should not be construed to be restricted only to a specific connection known in the art. However, all possible examples should be considered within the scope of the present invention.

[0034] It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

CLAIMS:

1. A triaxial geocomposite testing apparatus for simultaneously calibrating multiple pressure transducers comprising:

a fluid retaining section extending between a top portion and a base having an inlet, an outlet, and a plurality of spaced apart lateral openings formed therein, a fluid having a pressure tillable within the fluid retaining section through the inlet and dischargeable therefrom through the outlet, at least one pressure transducer insertable within the fluid retaining section through a corresponding opening for providing electrical signals during testing;

a pedestal attached to the base, the pedestal including at least one recess formed on its top surface and an internally formed first passageway connecting the at least one recess to a side opening of the pedestal, the at least one recess having a first diameter and includes atleast one earth pressure transducer having a second diameter positionable therein, the first diameter being greater than the second diameter, the first passageway having an electric cable disposable therein for electrically connecting the earth pressure transducer to a pressure reading device positioned outside the apparatus, the electric cable extendable outside the testing apparatus through a corresponding opening within the base; and

a holding member disposed within the at least one recess for allowing the at least one earth pressure transducer to be tightly retained therein, actuation surface of the at least one earth pressure transducer levelled with a top surface of the holding member.

2. The triaxial geocomposite testing apparatus according to claim 1, wherein the base includes a plate detachably attached thereto, the plate defined by an outer surface, an inner surface, and a central opening, the plurality of lateral openings extending between the outer surface and the inner surface.

3. The triaxial geocomposite testing apparatus according to claim 2, wherein a pore pressure transducer is insertable within the fluid retaining section through its corresponding opening formed within the plate, the pore pressure transducer providing pressure signals to the pressure reading device during testing.

4. The triaxial geocomposite testing apparatus according to claim 1 , wherein the at least one recess formed in the pedestal includes at least two earth pressure transducers positionable therein, diameters of both the earth pressure transducers being less than the first diameter, and wherein the holding member tightly retaining both the earth pressure transducers therein.

5. The triaxial geocomposite testing apparatus according to claim 1 , wherein the holding member has at least one circular slot corresponding to the shape of the at least one earth pressure transducer for accommodating the atleast one earth pressure transducer therein.

6. A triaxial geocomposite testing apparatus for simultaneously calibrating multiple pressure transducers comprising:

a fluid retaining section extending between a top portion and a base having an inlet, an outlet, a fluid having a pressure fillable within the fluid retaining section through the inlet and dischargeable therefrom through the outlet;

a plate defined by an outer surface, an inner surface, and a central opening, and being detachably attached to the base, the plate including a plurality of spaced apart lateral openings extending between the outer surface and the inner surface, at least one pressure transducer insertable within the fluid retaining section through the corresponding lateral opening, the atleast one pressure transducer providing pressure signals during testing to a pressure reading device positioned outside the testing apparatus; and

a pedestal attached to the base, the pedestal including at least one recess formed on its top surface and an internally formed first passageway connecting the at least one recess to a side opening of the pedestal, the at least one recess having at least one earth pressure transducer tightly positionable therein and the first passageway having an electric cable disposable therein, the electric cable connecting the earth pressure transducer to a pressure reading device positioned outside the apparatus, the electric cable extendable outside the testing apparatus through a corresponding opening within the base.

7. The triaxial geocomposite testing apparatus according to claim 6, wherein a pore pressure transducer is insertable within the fluid retaining section through its corresponding opening formed within the plate, the second pore pressure transducer providing pressure signals to the pressure reading device during testing.

8. The triaxial geocomposite testing apparatus according to claim 6, wherein the testing apparatus further includes a second passageway and a third passageway, both the second and the third passageways internally extending between a portion of the pedestal adjacent to the at least one recess and an external surface of the base, and wherein both the second and the third passageways connectable to a corresponding channel outside the apparatus.

9. The triaxial geocomposite testing apparatus according to claim 8, wherein the channel connecting the second passageway has a second pore pressure transducer disposed therein for measuring internal pore pressure of a geocomposite specimen positioned on the pedestal under loading condition of the apparatus, and wherein the channel connecting the third passageway is connected to volume change measurement apparatus.

10. The triaxial geocomposite testing apparatus according to claim 6, wherein the at least one recess formed on the pedestal has a first diameter and includes atleast one earth pressure transducer having a second diameter positionable therein, the first diameter being greater than the second diameter, and wherein a holding member is disposed within the at least one recess allowing the at least one earth pressure transducer to be tightly retained therein.

1 1. The triaxial geocomposite testing apparatus according to claim 1 1, wherein the holding member includes at least one circular slot corresponding to the shape of the at least one earth pressure transducer for accommodating the atleast one earth pressure transducer within the at least one recess.