Roadbed soft rock filler crushing value estimation method considering coarse and fine particle content

Abstract

The invention discloses a roadbed soft rock filler crushing value estimation method considering the content of coarse and fine particles, which comprises the following steps: S1, for a filled soft rock filler roadbed, determining the compaction dry density rho d by adopting a sand filling method, and determining the maximum dry density through an indoor compaction test to obtain a compaction coefficient; s2, performing a particle screening test on the roadbed soft rock filler to obtain the ratio of the mass of coarse particles with the particle size not smaller than 2.5 mm to the total mass; s3, through a point load test, measuring the point load strength of coarse-particle rocks in not less than 6 soft rock fillers, and obtaining the uniaxial compressive strength of the rocks and the average value of the uniaxial compressive strength of the rocks; and S4, estimating the crushing value of the roadbed soft rock filler according to the compaction coefficient of the roadbed soft rock filler, the mass ratio of the coarse particles and the average value of the uniaxial compressive strength of the rock blocks. According to the method, the influence of the strength of the coarse particle rock, the proportion of coarse and fine particles and the compaction density on the crushing value can be comprehensively considered. The test verifies that the method has good applicability.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering, and in particular relates to a method for estimating the crushing value of soft rock filler for roadbed taking into account the influence of multiple factors such as coarse and fine particle content. Background Art

[0002] A large number of engineering practices and scientific studies have shown that the crushing behavior of particles will cause changes in the gradation of roadbed fillers, thereby affecting their physical and mechanical properties. Specifically, the small particles generated after the coarse particles are crushed and filled into the filler pores, which will cause the filler pores to decrease and cause deformation. Therefore, the crushing behavior of coarse particles will aggravate the post-construction settlement of the roadbed, thereby affecting the smoothness of the railway track and the flatness of the highway pavement. Compared with the coarse particle fillers of hard rock with higher strength, the crushing phenomenon of coarse particles in the roadbed soft rock fillers is more serious.

[0003] Soft rocks are widely distributed at home and abroad, such as volcanic rocks such as tuff, sedimentary rocks such as red bed soft rocks, and metamorphic rocks such as phyllite, which are all complex rock masses with significant plastic deformation under specific environments. The Engineering Rock Mass Classification Standard GB / T50218-2014 classifies rock masses according to the saturated uniaxial compressive strength of rocks, and stipulates that rocks with a saturated uniaxial compressive strength of less than 30MPa are called soft rocks. Among them, rocks with a saturated uniaxial compressive strength of 15MPa to 30MPa are relatively soft rocks, rocks with a saturated uniaxial compressive strength of 5MPa to 15MPa are soft rocks, and rocks with a saturated uniaxial compressive strength of less than 5MPa are extremely soft rocks. With the large-scale construction of transportation infrastructure in soft rock areas, the applicability of crushed particles of soft rock mass as roadbed fillers has attracted much attention. Compared with intact rock mass, soft rock particle fillers as filling bodies are not continuously and uniformly stressed under load, but are mainly random contact transmission between edges and corners of particles, with obvious stress concentration, which is easy to cause particle crushing behavior. According to the Highway Roadbed Design Specifications JTG D30-2015, the rock filling material with a saturated uniaxial compressive strength of 5MPa to 30MPa is defined as soft rock material based on the saturated uniaxial compressive strength of the parent rock. The thickness of the filling layer and the compaction control standard for the upper and lower embankment layers of the roadbed are specified. According to the Railway Roadbed Design Specifications TB10001-2016, the coarse and coarse-grained soil filling materials with a saturated uniaxial compressive strength of the parent rock of rock particles less than 20MPa are considered as Groups C and D, and the compaction parameters of the roadbed filling should be determined in combination with tests and regional experience. It can be seen that the applicability of soft rock filling materials with low strength of coarse-grained rock blocks for roadbed filling still needs attention.

[0004] The particles in the roadbed filler are not in a single particle size range, but a mixture of particles of different sizes. With the decrease in the proportion of fine particles in the filler or the increase in the proportion of coarse particles, there are three types of soil structures in the filler after roadbed compaction: ① Suspended-dense structure, that is, the proportion of fine particles is high, and coarse particles are suspended in fine particles; ② Skeleton-dense structure, that is, the coarse particles are in close contact with each other and form a force-bearing skeleton, and the fine particles are densely filled in the pores between the coarse particles; ③ Skeleton-pore structure, that is, the proportion of coarse particles is high, and the content of fine particles is not enough to fill the pores between coarse particles. Obviously, with the increase in the proportion of coarse particles in the roadbed filler, the transfer of the roadbed load between particles gradually changes to being dominated by coarse particles, which aggravates the crushing behavior of coarse particles in soft rock. Therefore, the content of coarse or fine particles is also an important reason affecting the particle crushing in the roadbed soft rock filler.

[0005] The compaction density is crucial to the filling quality of roadbed projects. Among them, the compaction coefficient is quantified by the ratio of the dry density after compaction to the maximum dry density obtained by the indoor standard compaction test. It is an important indicator of the compaction quality of roadbed filling construction that is widely used both at home and abroad. From a microscopic perspective, as the compaction coefficient increases, the contact between the particles inside the filler becomes closer, and the number of contacts between the soil particles and the surrounding adjacent particles increases. As a result, the increase in the compaction coefficient will increase the transfer of the roadbed's load between particles, reduce the contact force between particles, and reduce the risk of crushing of coarse soft rock particles. It can be seen that the compaction coefficient is also a factor that affects the crushing of particles in the roadbed soft rock filler.

[0006] In order to ensure the good road performance of the roadbed filling body under the influence of engineering loads and environmental factors, the railway and highway industries have stipulated the crushing resistance index of coarse particles in the roadbed filling. Among them, the crushing value CA is an important indicator to measure the crushing resistance of coarse particles in the roadbed filling, and is used to evaluate the applicability of coarse particle filling in the roadbed in the project. Specifically, the crushing value CA is the percentage of mass loss after crushing with particles of standard particle size as the test object, using the specified test mold and load. Among them, the "Highway Engineering Aggregate Test Code" JTG E42-2005 uses coarse particles of 9.5mm to 13.2mm for testing, and the "Railway Crushed Stone Ballast Test Method" TB / T2328-2008 uses coarse particles of 10mm to 16mm for testing. The problem is that the existing crushing value test methods all use coarse particles of a specified single particle group as the test object, which only reflects the influence of a single factor of the strength of coarse-grained rock blocks, and does not consider the influence of multiple factors such as the proportion of coarse and fine particles in the filler and the compaction density of the filler. As a result, it is impossible to comprehensively and accurately evaluate the crushing resistance of coarse particles in the soft rock filler of the roadbed.

[0007] Therefore, innovating a method for estimating the crushing value of soft rock filler in the roadbed that can comprehensively reflect the influence of multiple factors such as the strength of coarse-grained rock blocks, the proportion of coarse and fine particles, and the compaction density has reference value and guiding significance for the reliable design and safe construction of roadbed projects. Summary of the invention

[0008] The present invention provides a method for estimating the crushing value of soft rock filler for roadbed, which takes into account the influence of multiple factors such as the content of coarse and fine particles. It solves the problem that the existing crushing value test method cannot comprehensively consider the physical and mechanical properties such as the strength of coarse-grained rock blocks, the proportion of coarse and fine particles, and the compaction density of the filler to evaluate the crushing resistance of soft rock filler for roadbed.

[0009] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method for estimating the crushing value of roadbed soft rock filler considering the coarse and fine particle content, comprising the following steps:

[0010] S1. For the soft rock filler roadbed that has been filled, the dry density ρ of the soft rock filler of the roadbed is determined by the sand filling method. d , the maximum dry density ρ of the soft rock filler of the roadbed is obtained through indoor compaction test dmax , obtain the compaction coefficient K = ρ of the soft rock filling material of the roadbed d / ρ dmax ;

[0011] S2. Conduct particle screening test on roadbed soft rock filler sample to obtain the mass of coarse particles m c The ratio P of the total mass of the sample m0 c =m c / m0;

[0012] S3. Through point load test, the point load strength I of coarse-grained rock blocks in soft rock filling of roadbed is determined s , determine the uniaxial compressive strength R of the coarse-grained rock mass c =23.9I s , and the average uniaxial compressive strength of the coarse-grained rock mass is obtained

[0013] S4, based on the compaction coefficient K of the roadbed soft rock filler and the mass proportion P of the coarse particles c , Average uniaxial compressive strength of rock blocks Estimate the crushing value CA of soft rock fill in roadbed.

[0014] Furthermore: in said S1, the indoor compaction test is carried out according to the standard technical parameters of the heavy Z3 compaction test.

[0015] Furthermore: in said S2, the particle size of the coarse particles is not less than 2.5 mm.

[0016] Further: In S3, the size and shape of the coarse-grained rock block in the point load test should meet the following requirements:

[0017] (1) The size of coarse-grained rock blocks is quantified by the loading point spacing D, which is the distance between the loading cones of the point load tester at the beginning of the point load test. The loading point spacing D is in the range of 35 mm to 80 mm.

[0018] (2) The shape of coarse-grained rock blocks is quantified by the shape coefficient β. The shape coefficient β = D / W, which is the ratio of the loading point spacing D to the minimum cross-sectional width W of the rock block. The shape coefficient β is determined according to the degree of weathering of the rock block: when the rock block is strongly weathered, the shape coefficient β satisfies 0.4 to 1.0; when the rock block is weakly weathered, the shape coefficient β satisfies 0.5 to 1.0; when the rock block is slightly weathered, the shape coefficient β satisfies 0.6 to 1.0.

[0019] Further: In S3, the point load strength I of the coarse-grained rock blocks in the roadbed soft rock filler is s =P / (D·W f ), where P is the failure load of the point load test, W f is the width of the rock failure section;

[0020] Further: In S3, the average uniaxial compressive strength of the coarse-grained rock blocks in the roadbed soft rock filler is Where n is the number of coarse-grained rock blocks in the point load test, n≥6;

[0021] Further: In said S4, the crushing value of the soft rock filler of the roadbed is estimated Where e is the base of natural logarithm.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention provides a method for estimating the crushing value of soft rock filler for roadbed, which takes into account the influence of multiple factors such as the content of coarse and fine particles. Compared with the traditional test method that only reflects the influence of a single factor of the strength of coarse-grained rock blocks, the present estimation method can comprehensively consider the influence of parameter indicators such as the strength of coarse-grained rock blocks in the soft rock filler, the proportion of coarse and fine particles, and the compaction density of the filler on the crushing value. As the strength of the coarse-grained rock blocks in the soft rock filler increases, the content of fine particles increases, and the compaction coefficient of the filler increases, the crushing resistance of the soft rock filler increases accordingly, that is, the crushing value decreases. After analysis and verification, the method of the present invention is reasonable and feasible.

[0024] (2) The parameter indicators in the present invention can be obtained based on the test equipment and methods in the current railway and highway and other related industry specifications, that is, the parameter indicators required in the estimation method, which is operational.

[0025] (3) The method of the present invention is easy to operate, has clear physical meaning, and has high estimation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flow chart of a method for estimating the crushing value of soft rock filler for roadbed taking into account the coarse and fine particle content. DETAILED DESCRIPTION

[0027] The specific implementation modes of the present invention are further described below to facilitate the understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0028] like Figure 1 As shown, in an embodiment of the present invention, a method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content includes the following steps:

[0029] S1. For the soft rock filler roadbed that has been filled, the dry density ρ of the soft rock filler of the roadbed is determined by the sand filling method. d , the maximum dry density ρ of the soft rock filler of the roadbed is obtained through indoor compaction test dmax , obtain the compaction coefficient K = ρ of the soft rock filling material of the roadbed d / ρ dmax ;

[0030] S2. Conduct particle screening test on roadbed soft rock filler sample to obtain the mass of coarse particles m c The ratio P of the total mass of the sample m0 c =m c / m0;

[0031] S3. Through point load test, the point load strength I of coarse-grained rock blocks in soft rock filling of roadbed is determined s , determine the uniaxial compressive strength R of the coarse-grained rock mass c =23.9I s , and the average uniaxial compressive strength of the coarse-grained rock mass is obtained

[0032] S4, based on the compaction coefficient K of the roadbed soft rock filler and the mass proportion P of the coarse particles c , Average uniaxial compressive strength of rock blocks Estimate the crushing value CA of soft rock fill in roadbed.

[0033] In S1, the indoor compaction test is carried out according to the standard technical parameters of the heavy Z3 compaction test.

[0034] This example mainly uses the "compaction test" method in the "Railway Engineering Geotechnical Test Code" TB10102-2010 as a reference standard, and adopts the heavy Z3 compaction test standard technical parameters. Specifically: hammer mass 4.5kg, hammer bottom diameter 51mm, drop distance 457mm; compaction cylinder inner diameter 152mm, cylinder height 116mm, volume 2103.9cm 3 ; compaction work 2701kJ / m 3 , the compaction layers are divided into 3 layers, and the number of strikes in each layer is 94.

[0035] In the S2, the particle size of the coarse particles is not less than 2.5 mm.

[0036] This embodiment mainly uses the "Standard Aggregate Crushing Rate Test" method in "Railway Crushed Stone Ballast Test Method" TB / T 2328-2008 as a reference standard. A coarse-grained standard aggregate of 10mm to 16mm is used for the crushing test. The coarse-grained standard aggregate after the crushing test is sampled through a sieve with a side length of 2.5mm. The crushing value is the ratio of the mass of crushed particles with a particle size of less than 2.5mm to the total mass of the standard aggregate before loading.

[0037] In S3, the size and shape of the coarse-grained rock block in the point load test shall meet the following requirements:

[0038] (1) The size of coarse-grained rock blocks is quantified by the loading point spacing D. The loading point spacing D is the distance between the loading cones of the point load tester at the beginning of the loading. The loading point spacing D is in the range of 35 mm to 80 mm.

[0039] (2) The shape of coarse-grained rock blocks is quantified by the shape coefficient β. The shape coefficient β = D / W, which is the ratio of the loading point spacing D to the minimum cross-sectional width W of the rock block. The shape coefficient β is determined according to the degree of weathering of the rock block: when the rock block is strongly weathered, the shape coefficient β satisfies 0.4 to 1.0; when the rock block is weakly weathered, the shape coefficient β satisfies 0.5 to 1.0; when the rock block is slightly weathered, the shape coefficient β satisfies 0.6 to 1.0.

[0040] In this embodiment, the relevant specifications have specific requirements for the size and shape selection of rock block specimens for point load tests. Regarding the size of rock blocks, the "Engineering Rock Test Method Standard" GB / T 50266-2013 recommends that the spacing between rock block loading points should be 15mm to 85mm, and the ratio of the spacing between loading points to the average width should be 0.3 to 1.0; the "Railway Engineering Rock Test Procedure" TB10115-2014 recommends that the spacing between rock block loading points should be 15mm to 100mm, and the ratio of the spacing between loading points to the average width should be 0.3 to 1.0; the "Highway Engineering Rock Test Procedure" JTG-E41-2005 recommends that the spacing between rock block loading points should be 15mm to 100mm, and the ratio of the spacing between loading points to the average width should be 0.3 to 1.0. Based on the relevant specifications, a large number of point load tests were carried out on rock blocks with different degrees of weathering, and statistical analysis found that:

[0041] ① When the spacing between the rock block loading points is in the range of 35mm to 80mm, the point load strength of the rock block is less affected by the geometric dimensions, and the deviation of the point load strength test value is relatively small.

[0042] ②The influence of rock shape coefficient on point load strength is closely related to the degree of weathering. The shape coefficient of strongly weathered rock is between 0.4 and 1.0, the shape coefficient of weakly weathered rock is between 0.5 and 1.0, and the shape coefficient of slightly weathered rock is between 0.6 and 1.0. The relative deviation of the point load strength test value is small.

[0043] In S3, the point load strength I of the coarse-grained rock blocks in the soft rock filler of the roadbed s =P / (D·W f ), where P is the failure load of the point load test, W f is the width of the rock failure section;

[0044] In this embodiment, based on the mechanical essence of point load strength, the failure area should be the actual failure cross-sectional area of ​​the rock block sample. For soft rock coarse-grained rock blocks, due to the different mineral components of the rocks, point load tests usually do not break along the smallest cross section. s It is more reasonable to express it by the ratio of the failure load to the actual failure cross-sectional area. The failure cross-sectional area of ​​the rock sample is expressed by the ratio of the loading point spacing D to the failure cross-sectional width W. f The product of is approximated.

[0045] In S3, the average uniaxial compressive strength of the coarse-grained rock blocks in the roadbed soft rock filler is Where n is the number of coarse-grained rock blocks in the point load test, n≥6;

[0046] In this embodiment, in order to well reflect the point load strength I of the coarse-grained rock block of the soft rock filler, s Uniaxial compressive strength R of rockc The relationship between the uniaxial compressive strength and the point load strength test of slightly weathered soft rock that can be prepared into cylindrical specimens was compared, and the uniaxial compressive strength of the parent rock R c Point load strength I s At the same time, in order to ensure the representativeness of the strength of the coarse-grained rock blocks of the soft rock filler, the point load strength of no less than 6 rock blocks should be randomly tested to obtain the average uniaxial compressive strength of the rock blocks.

[0047] In S4, the crushing value of the soft rock filler in the roadbed is estimated Where e is the base of natural logarithm.

[0048] In this embodiment, the estimated crushing value CA of the roadbed soft rock filler has a limited range of use, which is applicable to the uniaxial compressive strength R of the coarse-grained rock block. c The ratio of the mass of coarse particles with a particle size greater than 2.5 mm to the total mass at 5-30 MPa is P c The mass ratio of coarse particles is between 0.3 and 1.0, and the packing compaction coefficient is between 0.90 and 1.00. c There is a significant nonlinear effect on the crushing value CA, and the coarse particle mass proportion P c Perform an exponential transformation and let it be Can be converted into a linear relationship; for multiple groups of coarse-grained rock strength And quality ratio The crushing value data of soft rock filler in the roadbed with the change of filler compaction coefficient K and other parameter indicators were used for regression analysis, and the constant term in the regression equation was 30.68, and the factor term The coefficients of K are -0.33, 0.89, and -23.97 respectively.

[0049] The following example verifies that for the soft rock filler of the roadbed at a railway construction site, the filler compaction coefficient K, the mass proportion of coarse particles P and the filler compaction coefficient K are calculated according to claims S1, S2 and S3. c , average rock strength The crushing value CA is estimated according to S4. At the same time, the crushing value test is verified for the roadbed soft rock filler under the same conditions. The relevant tests in the claims are carried out with reference to the "Railway Engineering Geotechnical Test Regulations" TB10102, "Railway Engineering Rock Test Regulations" TB10115, and "Railway Crushed Stone Ballast Test Method" TB / T2328. The specific data of the embodiment are as follows.

[0050] Embodiment 1:

[0051] According to step S1, the compacted dry density ρ of the soft rock filler at a railway subgrade construction site is measured. d=1.529g / cm 3 , maximum dry density ρ dmax =1.692g / cm 3 , the compaction coefficient of the soft rock filler K≈0.90; according to step S2, the total mass of the soft rock filler sample m0=1544.65g is taken, and the mass m of coarse particles with a particle size greater than 2.5mm is screened out. c =1529.72g, the mass proportion of coarse particles in soft rock filler is P c =99.03%; According to step S3, take the coarse-grained rock block in the soft rock filler and measure the load strength I s They are 0.76MPa, 0.78MPa, 0.74MPa, 0.77MPa, 0.73MPa and 0.80MPa respectively, and the average uniaxial compressive strength of coarse-grained rock blocks in soft rock fillers is obtained. According to step S4, the crushing value of the soft rock filler of the roadbed is estimated

[0052] For the same soft rock filler for roadbed, a crushing test was carried out at the corresponding compaction density, and the measured crushing value was 20.96%; the estimated value deviated from the measured data by about 0.51%, which is not a large error.

[0053] Similarly, a traditional standard crushing test was conducted on the coarse particles in the same roadbed soft rock filler, and the measured crushing value was 18.74%; compared with the estimated value that comprehensively considers the influence of multiple factors such as the strength of coarse-grained rock blocks, the mass proportion of coarse particles and the compaction density of the filler, the deviation of the traditional standard crushing test value increased to 1.71%.

[0054] Embodiment 2:

[0055] According to step S1, the compacted dry density ρ of the soft rock filler at a railway subgrade construction site is measured. d =1.836g / cm 3 , maximum dry density ρ dmax =1.935g / cm 3 , the compaction coefficient of the soft rock filler K≈0.95; according to step S2, the total mass of the soft rock filler sample m0=1987.79g is taken, and the mass m of coarse particles with a particle size greater than 2.5mm is screened out. c =1392.05g, the mass proportion of coarse particles in soft rock filler is P c =70.03%; According to step S3, take the coarse-grained rock block in the soft rock filler and measure the load strength I s They are 1.26MPa, 1.31MPa, 1.28MPa, 1.27MPa, 1.29MPa, and 1.32MPa respectively, and the average uniaxial compressive strength of the coarse-grained rock blocks in the soft rock filler is obtained. According to step S4, the crushing value of the soft rock filler of the roadbed is estimated

[0056] For the same soft rock filler for roadbed, a crushing test was carried out at the corresponding compaction density, and the measured crushing value was 5.68%; the estimated value deviated from the measured data by about 0.66%, which is not a large error.

[0057] Similarly, a traditional standard crushing test was conducted on the coarse particles in the same roadbed soft rock filler, and the measured crushing value was 12.98%; compared with the estimated value that comprehensively considers the influence of multiple factors such as the strength of coarse-grained rock blocks, the mass proportion of coarse particles and the compaction density of the filler, the deviation of the traditional standard crushing test value increased to 7.96%.

[0058] Embodiment 3:

[0059] According to step S1, the compacted dry density ρ of the soft rock filler at a railway subgrade construction site is measured. d =1.992g / cm 3 , maximum dry density ρ dmax =1.997g / cm 3 , the soft rock filler compaction coefficient K≈1.00; according to step S2, the total mass of the soft rock filler sample m0=2261.18g is taken, and the mass m of coarse particles with a particle size greater than 2.5mm is screened out. c =679.71g, the mass proportion of coarse particles in soft rock filler is P c =30.06%; According to step S3, take the coarse-grained rock block in the soft rock filler and measure the load strength I s They are 0.31MPa, 0.29MPa, 0.32MPa, 0.27MPa, 0.30MPa and 0.28MPa respectively, and the average uniaxial compressive strength of coarse-grained rock blocks in soft rock fillers is obtained. According to step S4, the crushing value of the soft rock filler of the roadbed is estimated

[0060] For the same soft rock filler for roadbed, a crushing test was carried out at the corresponding compaction density, and the crushing value was measured to be 6.24%; the estimated value deviated from the measured data by about 0.34%, which is not a large error.

[0061] Similarly, a traditional standard crushing test was conducted on the coarse particles in the same roadbed soft rock filler, and the measured crushing value was 23.89%; compared with the estimated value that comprehensively considers the influence of multiple factors such as the strength of coarse-grained rock blocks, the mass proportion of coarse particles and the compaction density of the filler, the deviation of the traditional standard crushing test value increased to 17.31%.

[0062] The examples all show that the estimated crushing value of the roadbed soft rock filler according to the claims is slightly different from the crushing test value under the same material and compaction conditions, indicating that the "a method for estimating the crushing value of the roadbed soft rock filler considering the coarse and fine particle content" proposed in the present invention has good adaptability. The traditional standard crushing test value, because it does not consider the influence of factors such as particle grading and filler density, has a significant deviation from the actual situation when the coarse particle mass ratio is low and the filler compaction density is high.

[0063] Based on the above analysis, the method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content proposed in the present invention is reasonable and feasible.

[0064] Working principle and process of the present invention: For the soft rock filler roadbed that has been filled, the compacted dry density ρ is measured by the sand filling method. d , the maximum dry density ρ is determined by indoor compaction test dmax , get the compaction coefficient of soft rock filling material of roadbed K = ρ d / ρ dmax ; Carry out particle screening test on soft rock filling material of roadbed, and obtain the mass m of coarse particles larger than 2.5 mm c The ratio P of the total mass m0 c =m c / m0; Through point load test, the point load strength I of coarse-grained rock blocks in soft rock filling of roadbed is determined s , the uniaxial compressive strength R of no less than 6 rock blocks is obtained c =23.9I s and its average value According to the compaction coefficient K of the filler and the mass proportion P of the coarse particles c , Average uniaxial compressive strength of rock blocks Estimating the crushing value of soft rock fill in roadbed Compared with the traditional method for testing the crushing value of coarse-grained filler in roadbed, the present invention can comprehensively consider the influence of factors such as the strength of coarse-grained rock blocks, the proportion of coarse and fine particles, and the compaction density of filler in the roadbed soft rock filler on the crushing value. The test results show that the estimation method of the present invention has good engineering applicability.

[0065] The beneficial effects of the present invention are:

[0066] (1) The present invention provides a method for estimating the crushing value of soft rock filler for roadbed, which takes into account the influence of multiple factors such as the content of coarse and fine particles. Compared with the traditional test method that only reflects the influence of a single factor of the strength of coarse-grained rock blocks, the present estimation method can comprehensively consider the influence of parameter indicators such as the strength of coarse-grained rock blocks in the soft rock filler, the proportion of coarse and fine particles, and the compaction density of the filler on the crushing value. As the strength of the coarse-grained rock blocks in the soft rock filler increases, the content of fine particles increases, and the compaction coefficient of the filler increases, the crushing resistance of the soft rock filler increases accordingly, that is, the crushing value decreases. After analysis and verification, the method of the present invention is reasonable and feasible.

[0067] (2) The parameter indicators in the present invention can be obtained based on the test equipment and methods in the current railway and highway and other related industry specifications, that is, the parameter indicators required in the estimation method, which is operational.

[0068] (3) The method of the present invention is easy to operate, has clear physical meaning, and has high estimation accuracy.

[0069] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "thickness", "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", "radial", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying the relative importance or the number of implicitly specified technical features. Therefore, the features defined by "first", "second", "third", etc. may explicitly or implicitly include one or more of the features.

Claims

1. A method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content, characterized in that: The following steps are involved: S1. For the soft rock filler roadbed that has been filled, the dry density ρ of the soft rock filler of the roadbed is determined by the sand filling method. d , the maximum dry density ρ of the soft rock filler of the roadbed is obtained through indoor compaction test dmax , obtain the compaction coefficient K = ρ of the soft rock filling material of the roadbed d / ρ dmax ; S2. Conduct particle screening test on roadbed soft rock filler sample to obtain the mass of coarse particles m c The ratio P of the total mass of the sample m0 c =m c / m0; S3. Through point load test, the point load strength I of coarse-grained rock blocks in soft rock filling of roadbed is determined s , determine the uniaxial compressive strength R of the coarse-grained rock mass c =23.9I s , and the average uniaxial compressive strength of the coarse-grained rock mass is obtained S4, based on the compaction coefficient K of the roadbed soft rock filler and the mass proportion P of the coarse particles c , Average uniaxial compressive strength of rock blocks Estimate the crushing value CA of soft rock fill in roadbed.

2. The method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content according to claim 1 is characterized in that: In S1, the indoor compaction test is carried out according to the standard technical parameters of the heavy Z3 compaction test.

3. The method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content according to claim 1, characterized in that: In the S2, the particle size of the coarse particles is not less than 2.5 mm.

4. The method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content according to claim 1, characterized in that: In S3, the size and shape of the coarse-grained rock block in the point load test shall meet the following requirements: (1) The size of coarse-grained rock blocks is quantified by the loading point spacing D, which is the distance between the loading cones of the point load tester at the beginning of the point load test. The loading point spacing D is in the range of 35 mm to 80 mm. (2) The shape of coarse-grained rock blocks is quantified by the shape coefficient β. The shape coefficient β = D / W, which is the ratio of the loading point spacing D to the minimum cross-sectional width W of the rock block. The shape coefficient β is determined according to the degree of weathering of the rock block: when the rock block is strongly weathered, the shape coefficient β satisfies 0.4 to 1.0; when the rock block is weakly weathered, the shape coefficient β satisfies 0.5 to 1.0; when the rock block is slightly weathered, the shape coefficient β satisfies 0.6 to 1.

0.

5. The method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content according to claim 1, characterized in that: In S3, the point load strength I of the coarse-grained rock blocks in the soft rock filler of the roadbed s =P / (D·W f ), where P is the failure load of the point load test, W f is the width of the rock failure section.

6. The method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content according to claim 1, characterized in that: In S3, the average uniaxial compressive strength of the coarse-grained rock blocks in the roadbed soft rock filler is Where n is the number of coarse-grained rock blocks in the point load test, n≥6.

7. The method for estimating the crushing value of soft rock filler for roadbed considering the coarse and fine particle content according to claim 1, characterized in that: In S4, the crushing value of the soft rock filler in the roadbed is estimated Where e is the base of natural logarithm.

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