A test method for obtaining soil compression modulus

Abstract

The present invention discloses a test method for obtaining soil compression modulus, which relates to the field of soil testing technology. The method comprises: excavating a test pit of set size at a project site, pouring expansive concrete containing a set amount of expansive agent in the test pit; during the solidification process of the expansive concrete, obtaining the test pressure values ​​of multiple test points on the side wall of the test pit, and when any test pressure value reaches each set pressure value, recording the test pressure value and deformation amount of each test point at this time; obtaining the soil compression modulus based on the test pit size, the initial porosity of the soil, and the test pressure value and deformation amount of each test point corresponding to each set pressure value. This solves the problem in the prior art that after collecting soil samples from the project construction site, the soil samples need to be re-prepared in the laboratory, and the soil is disturbed, resulting in a loss of accuracy in the test results.

Description

Technical Field

[0001] The present invention relates to the technical field of soil testing, and in particular to a testing method for obtaining soil compression modulus. Background Art

[0002] The compression modulus is an important indicator for determining soil compressibility and calculating foundation compression deformation. The smaller the soil's compression modulus, the higher its compressibility. Because soil is compressible, the impact of the stress distribution in the foundation soil under the action of upper loads on the soil's compression process must be considered when calculating foundation settlement. Therefore, soil compressibility is crucial for calculating foundation settlement.

[0003] In the existing technology, the compression modulus of soil is generally obtained through indoor consolidation tests. This requires collecting soil samples from the project construction site and then re-preparing the soil samples in the laboratory. During this process, the soil is disturbed, which affects the accuracy of the test results. Summary of the Invention

[0004] In response to the defects existing in the prior art, the purpose of the present invention is to provide a test method for obtaining the compression modulus of soil, which can solve the problem in the prior art that after collecting soil samples from the project construction site, the soil is disturbed during the process of re-preparing the soil samples in the laboratory, resulting in a loss of accuracy of the test results.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] This scheme provides a test method for obtaining the compression modulus of soil, including:

[0007] Excavate a test pit of set size at the project site, and pour expansive concrete containing a set amount of expansive agent into the test pit;

[0008] During the solidification process of the expansive concrete, the test pressure values ​​at multiple test points on the side wall of the test pit are obtained. When any test pressure value reaches the set pressure value, the test pressure value and deformation of each test point at this time are recorded;

[0009] The soil compression modulus is obtained based on the test pit size, the initial porosity of the soil, and the test pressure value and deformation amount of each test point corresponding to each set pressure value.

[0010] In some optional solutions, the soil compression modulus is obtained based on the test pit size, the initial porosity of the soil, and the test pressure value and deformation amount of each test point corresponding to each set pressure value, including:

[0011] According to the detection pressure value of each detection point at each measurement time, the average pressure on the soil at each measurement time is obtained;

[0012] According to the test pit size and the deformation of each detection point at each measurement time, the volume of the expansive concrete at each measurement time is obtained;

[0013] The soil compression modulus is obtained according to the average pressure, the volume of the expansive concrete, the size of the test pit, and the initial porosity of the soil.

[0014] In some optional solutions, the test pit is a rectangular parallelepiped, and the detection points are arranged at the upper, middle and lower parts of the middle positions of the four sides of the test pit, with a total of twelve detection points.

[0015] In some alternative solutions, according to the formula:

[0016]

[0017] Obtain the average pressure on the soil at each measurement moment;

[0018] in, is the average pressure on the soil at the i-th measurement moment, i = 1~n, n is the number of measurement moments, P lt is the pressure value of the upper left measuring point, P lm is the pressure value of the left middle measuring point, P lb is the pressure value of the lower left measuring point, P rt is the pressure value of the upper right measuring point, P rm is the pressure value of the right middle measuring point, P rb is the pressure value of the lower right measuring point, P ft is the pressure value of the upper front measuring point, P fm is the pressure value of the front middle measuring point, P fb is the pressure value of the front lower measuring point, P bt is the pressure value of the upper rear measuring point, P bm is the pressure value of the rear middle measuring point, P bb is the pressure value of the lower measuring point.

[0019] In some alternative solutions, according to the formula:

[0020] S it =(Δb lt +Δb rt +B)×(Δb ft +Δb bt +B)

[0021] S im =(Δb lm +Δb rm +B)×(Δb fm +Δb bm +B)

[0022] S ib =(Δblb ++Δb rb +B)×(Δb fb +Δb bb +B)

[0023]

[0024] Obtaining the volume of expansive concrete at each measurement moment;

[0025] Among them, S it is the horizontal cross-sectional area of ​​the expansive concrete at the upper measuring point at the i-th measuring moment, S im is the horizontal cross-sectional area of ​​the expansive concrete at the middle measuring point at the i-th measuring moment, S ib is the horizontal cross-sectional area of ​​the expansive concrete at the lower measuring point at the i-th measuring moment, Δb lt is the deformation of the upper left measuring point, Δb rt is the deformation of the upper right measuring point, Δb ft is the deformation of the upper front measuring point, Δb bt is the deformation of the upper rear measuring point, Δb lm is the deformation of the left middle measuring point, Δb rm is the deformation of the right middle measuring point, Δb fm is the deformation of the front-center measuring point, Δb bm is the deformation of the rear middle measuring point, Δb lb is the deformation of the lower left measuring point, Δb rb is the deformation of the lower right measuring point, Δb fb is the deformation of the front lower measuring point, Δb bb is the deformation of the lower measuring point, B is the side length of the test pit, V i is the volume of expansive concrete at the i-th measurement moment.

[0026] In some alternative solutions, according to the formula:

[0027] V d =3B×3B×BB 3 =8B 3 , ΔV i =V i -B 3

[0028]

[0029]

[0030]

[0031]

[0032] Obtain soil compression modulus;

[0033] Among them, V d is the volume of soil within the influence range of expansive concrete, ΔV i is the volume expansion of the expansive concrete at the i-th measurement moment, V v0 is the sum of the volumes of liquid and gas in the initial state of the soil, V s0 is the solid volume of the soil in the initial state, V vi is the sum of the volumes of liquid and gas after the soil is compressed at the i-th measurement moment, e0 is the initial porosity of the soil, e i is the soil porosity ratio at the i-th measurement moment, E s is the soil compression modulus, a v is the compression factor.

[0034] In some optional solutions, an inclinometer tube is vertically arranged in the middle of each of the four sides of the test pit to obtain the deformation amount; and a pressure sensor is arranged at each detection point to obtain the detection pressure value.

[0035] In some optional solutions, before pouring the expansive concrete containing the set amount of expansive agent in the test pit, a concrete cushion layer of a set thickness is poured at the bottom of the test pit.

[0036] In some optional solutions, lubricating oil is applied to the surface of the concrete cushion layer after the concrete cushion layer is completely solidified.

[0037] In some optional solutions, after pouring expansive concrete containing a set amount of expansive agent in the test pit, a ballast load is applied to the top of the test pit.

[0038] Compared with existing technologies, the advantages of the present invention are as follows: This solution excavates a test pit of set size at the project site and pours expansive concrete containing a set amount of expansive agent into the test pit; during the solidification process of the expansive concrete, the test pressure values ​​at multiple test points on the sidewall of the test pit are obtained. When any test pressure value reaches the set pressure value, the test pressure value and deformation amount of each test point at that time are recorded; and the soil compression modulus is obtained based on the test pit size, the initial porosity of the soil, and the test pressure values ​​and deformation amounts of each test point corresponding to the set pressure values. This solves the problem in existing technologies that the soil is disturbed during the process of collecting soil samples from the project construction site and then re-preparing soil samples in the laboratory, which affects the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] Figure 1 Schematic diagram of a flow chart of a test method for obtaining soil compression modulus in an embodiment of the present invention;

[0041] Figure 2 A schematic cross-sectional view of a test pit in an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the arrangement of the inclinometer casing in an embodiment of the present invention;

[0043] In the figure: 1. Test pit; 2. Inspection point; 3. Concrete cushion; 4. Ballast; 5. Inclinometer tube. DETAILED DESCRIPTION

[0044] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0045] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0046] like Figure 1 As shown, the present invention provides a test method for obtaining the compression modulus of soil, comprising:

[0047] S1: Excavate a test pit of set size at the project site and pour expansive concrete containing a set amount of expansive agent into the test pit.

[0048] In this embodiment, the dosage refers to the mass ratio of the expansive agent to the cement in the expansive concrete. The dosage is set to be no less than 50% and adjusted according to the actual project.

[0049] S2: During the solidification process of the expansive concrete, the test pressure values ​​of multiple test points on the side wall of the test pit are obtained. When any test pressure value reaches the set pressure value, the test pressure value and deformation of each test point at this time are recorded.

[0050] In this embodiment, there are multiple set pressure values.

[0051] S3: Obtain the soil compression modulus based on the test pit size, the initial porosity of the soil, and the test pressure value and deformation amount of each test point corresponding to each set pressure value.

[0052] Step S3 specifically includes:

[0053] S31: Obtain the average pressure on the soil at each measuring moment according to the detection pressure value of each detection point at each measuring moment.

[0054] S32: Obtain the volume of the expansive concrete at each measurement moment according to the test pit size and the deformation amount of each detection point at each measurement moment.

[0055] S33: Obtaining the soil compression modulus according to the average pressure, the volume of the expansive concrete, the test pit size, and the initial porosity of the soil.

[0056] like Figure 2 As shown, in some optional embodiments, the test pit 1 is a rectangular parallelepiped, and the detection points 2 are arranged at the upper, middle and lower parts of the middle positions of the four sides of the test pit 1, with a total of twelve detection points.

[0057] In some optional embodiments, according to the formula:

[0058]

[0059] Obtain the average pressure on the soil at each measurement moment;

[0060] in, is the average pressure on the soil at the i-th measurement moment, i = 1~n, n is the number of measurement moments, P lt is the pressure value of the upper left measuring point, P lm is the pressure value of the left middle measuring point, P lb is the pressure value of the lower left measuring point, P rt is the pressure value of the upper right measuring point, P rm is the pressure value of the right middle measuring point, P rb is the pressure value of the lower right measuring point, P ft is the pressure value of the upper front measuring point, P fm is the pressure value of the front middle measuring point, P fb is the pressure value of the front lower measuring point, P bt is the pressure value of the upper rear measuring point, P bm is the pressure value of the rear middle measuring point, P bb is the pressure value of the lower measuring point.

[0061] In some optional embodiments, according to the formula:

[0062] S it =(Δb lt +Δb rt+B)×(Δb ft +Δb bt +B)

[0063] S im =(Δb lm +Δb rm +B)×(Δb fm +Δb bm +B)

[0064] S ib =(Δb lb ++Δb rb +B)×(Δb fb +Δb bb +B)

[0065]

[0066] Obtaining the volume of expansive concrete at each measurement moment;

[0067] Among them, S it is the horizontal cross-sectional area of ​​the expansive concrete at the upper measuring point at the i-th measuring moment, S im is the horizontal cross-sectional area of ​​the expansive concrete at the middle measuring point at the i-th measuring moment, S ib is the horizontal cross-sectional area of ​​the expansive concrete at the lower measuring point at the i-th measuring moment, Δb lt is the deformation of the upper left measuring point, Δb rt is the deformation of the upper right measuring point, Δb ft is the deformation of the upper front measuring point, Δb bt is the deformation of the upper rear measuring point, Δb lm is the deformation of the left middle measuring point, Δb rm is the deformation of the right middle measuring point, Δb fm is the deformation of the front-center measuring point, Δb bm is the deformation of the rear middle measuring point, Δb lb is the deformation of the lower left measuring point, Δb rb is the deformation of the lower right measuring point, Δb fb is the deformation of the front lower measuring point, Δb bb is the deformation of the lower measuring point, B is the side length of the test pit, V i is the volume of expansive concrete at the i-th measurement moment.

[0068] In some optional embodiments, according to the formula:

[0069] V d =3B×3B×BB 3 =8B 3 , ΔV i =V i -B 3

[0070]

[0071]

[0072]

[0073]

[0074] Obtain soil compression modulus;

[0075] Among them, V d is the volume of soil within the influence range of expansive concrete, ΔV i is the volume expansion of the expansive concrete at the i-th measurement moment, V v0 is the sum of the volumes of liquid and gas in the initial state of the soil, V s0 is the solid volume of the soil in the initial state, V vi is the sum of the volumes of liquid and gas after the soil is compressed at the i-th measurement moment, e0 is the initial porosity of the soil, e i is the soil porosity ratio at the i-th measurement moment, E s is the soil compression modulus, a v is the compression factor.

[0076] In this embodiment, the test pit is a cube with equal length, width and height, which is convenient for measurement and calculation.

[0077] like Figure 3 As shown, in some optional embodiments, an inclinometer tube 5 is vertically arranged at the middle position of each of the four sides of the test pit 1 to obtain the deformation amount; and a pressure sensor is arranged at each detection point to obtain the detection pressure value.

[0078] like Figure 2 As shown, in some optional embodiments, before pouring the expansive concrete containing a set amount of expansive agent in the test pit, a concrete cushion layer 3 of a set thickness is poured at the bottom of the test pit.

[0079] In this embodiment, a concrete cushion layer 3 of a set thickness is poured at the bottom of the test pit to prevent the expansive concrete from expanding and deforming downward.

[0080] In some optional embodiments, after the concrete cushion layer 3 is completely solidified, lubricating oil is applied to the surface of the concrete cushion layer 3 .

[0081] In this embodiment, lubricating oil is applied to the surface of the concrete cushion layer 3 to facilitate separation of the expansive concrete from the concrete cushion layer 3 .

[0082] In some optional embodiments, after pouring expansive concrete containing a set amount of expansive agent in the test pit, a ballast 4 is applied to the top of the test pit.

[0083] In this embodiment, after pouring expansive concrete containing a set amount of expansive agent in the test pit 1, a ballast 4 is applied to the top of the test pit 1 to limit the deformation of the expansive concrete in the vertical direction.

[0084] In some optional embodiments, the expansive agent is a calcium sulfoaluminate concrete expansive agent.

[0085] In summary, this solution involves excavating a test pit of a set size at the project site, and pouring expansive concrete containing a set amount of expansive agent in the test pit; during the solidification process of the expansive concrete, obtaining the test pressure values ​​of multiple test points on the side wall of the test pit, and when any test pressure value reaches each set pressure value, recording the test pressure value and deformation amount of each test point at this time; obtaining the soil compression modulus based on the test pit size, the initial porosity of the soil, and the test pressure value and deformation amount of each test point corresponding to each set pressure value. This solves the problem in the prior art that the soil is disturbed during the process of re-preparing soil samples in the laboratory after collecting soil samples from the project construction site, which affects the accuracy of the test results. The test method provided by the present invention is simple to operate, requires only one test pit, and the test site occupies a small area. It can be applied to various types of sites such as flat land, valleys, hillsides, and undulating ground.

[0086] The following examples are provided to facilitate understanding of the present invention.

[0087] A 50cm x 50cm x 55cm test pit was excavated at the bottom of an open-cut tunnel. A 5cm-thick concrete cushion was poured at the bottom of the test pit. After the concrete cushion was completely solidified, a layer of lubricating oil was applied to its surface. Expansive concrete with a 50% expansive agent content was poured into the test pit. A 1.0-ton weight was used as ballast at the top of the test pit. During the test, the deformation and test pressure values ​​at each test point were recorded when the test pressure reached 50 kPa, 100 kPa, and 200 kPa. The data are shown in Tables 1, 2, 3, and 4. In Table 4, the compression modulus corresponding to a set pressure of 100 kPa refers to the soil compression modulus between 50 kPa and 100 kPa, and the compression modulus corresponding to a set pressure of 200 kPa refers to the soil compression modulus between 100 kPa and 200 kPa.

[0088] Table 1

[0089]

[0090]

[0091] Table 2

[0092]

[0093] Table 3

[0094]

[0095] Table 4

[0096]

[0097] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0098] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0099] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A test method for obtaining soil compression modulus, characterized in that: include: Excavate a test pit of set size at the project site, and pour expansive concrete containing a set amount of expansive agent into the test pit; During the solidification process of the expansive concrete, the test pressure values ​​at multiple test points on the side wall of the test pit are obtained. When any test pressure value reaches the set pressure value, the test pressure value and deformation of each test point at this time are recorded; The soil compression modulus is obtained based on the test pit size, the initial porosity of the soil, and the test pressure value and deformation amount of each test point corresponding to each set pressure value; The method of obtaining the soil compression modulus based on the test pit size, the initial porosity of the soil, and the detection pressure value and deformation amount of each detection point corresponding to each set pressure value includes: According to the detection pressure value of each detection point at each measurement time, the average pressure on the soil at each measurement time is obtained; According to the test pit size and the deformation of each detection point at each measurement time, the volume of the expansive concrete at each measurement time is obtained; Obtaining the soil compression modulus based on the average pressure, the volume of the expansive concrete, the test pit size, and the initial porosity of the soil; The test pit is a rectangular parallelepiped, and the detection points are arranged at the upper, middle and lower parts of the middle positions of the four sides of the test pit, with a total of twelve detection points; According to the formula: Obtain the average pressure on the soil at each measurement moment; in, For the The average pressure on the soil at the measurement moment is , To measure the number of moments, is the pressure value of the upper left measuring point, is the pressure value of the left middle measuring point, is the pressure value of the lower left measuring point, is the pressure value of the upper right measuring point, is the pressure value of the right middle measuring point, is the pressure value of the lower right measuring point, is the pressure value of the upper front measuring point, is the pressure value of the front-middle measuring point, is the pressure value of the front lower measuring point, is the pressure value of the upper measuring point, is the pressure value of the rear middle measuring point, is the pressure value of the rear lower measuring point; According to the formula: Obtaining the volume of expansive concrete at each measurement moment; in, For the The horizontal cross-sectional area of ​​the expansive concrete at the upper measuring point at each measuring moment is: For the The horizontal cross-sectional area of ​​the expansive concrete at the middle measuring point at each measuring moment is: For the The horizontal cross-sectional area of ​​the expansive concrete at the lower measuring point at each measuring moment is: is the deformation variable of the upper left measuring point, is the deformation variable of the upper right measuring point, is the deformation of the upper front measuring point, is the deformation of the upper rear measuring point, is the deformation variable of the left middle measuring point, is the deformation variable of the right middle measuring point, is the deformation of the front-center measuring point, is the deformation variable of the rear middle measuring point, is the deformation variable of the lower left measuring point, is the deformation variable of the lower right measuring point, is the deformation of the front lower measuring point, is the deformation of the lower measuring point, is the side length of the test pit, For the The volume of expanded concrete at each measurement moment; According to the formula: ， ， Obtain soil compression modulus; in, is the volume of soil within the influence range of expansive concrete, For the The volume expansion of the expansive concrete at each measurement moment is: is the sum of the volumes of liquid and gas in the initial state of the soil, is the solid volume of the soil in its initial state, For the The sum of the volumes of liquid and gas after the soil is compressed at each measurement moment, is the initial porosity ratio of the soil, For the The soil porosity ratio at the measurement moment is is the soil compression modulus, is the compression factor.

2. The test method for obtaining soil compression modulus according to claim 1, characterized in that: By vertically arranging an inclinometer tube in the middle of each of the four sides of the test pit, the deformation amount is obtained; and a pressure sensor is arranged at each detection point to obtain the detection pressure value.

3. The test method for obtaining soil compression modulus according to claim 1, characterized in that: Before pouring expansive concrete containing a set amount of expansive agent in the test pit, pour a concrete cushion layer of a set thickness at the bottom of the test pit.

4. The test method for obtaining soil compression modulus according to claim 3, characterized in that: After the concrete cushion layer is completely solidified, apply lubricating oil on the surface of the concrete cushion layer.

5. The test method for obtaining soil compression modulus according to claim 1, wherein: After pouring expansive concrete containing a set amount of expansive agent in the test pit, a ballast load is applied to the top of the test pit.

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