Screening method for carbonaceous shale formation filler for road use

Abstract

The present invention discloses a method for screening carbonaceous shale formation fillers for roads, wherein the carbonaceous shale formation includes original carbonaceous shale fillers, and the method includes: preliminarily screening the original carbonaceous shale fillers, and obtaining two-screened carbonaceous shale fillers according to the filler particle size; obtaining three-screened carbonaceous shale fillers according to the bearing ratio; and obtaining carbonaceous shale formation fillers for roads that match the corresponding roadbed according to the compression coefficient and consolidated undrained shear strength index of the three-screened carbonaceous shale fillers. The present invention conducts multiple tests on the original carbonaceous shale fillers of each section, and according to the use requirements of the road fillers, tests and screens out carbonaceous shale formation fillers for roads that meet the use requirements, thereby solving the problem that various diseases are prone to occur in the roadbed of carbonaceous shale fillers, realizing the construction and utilization of carbonaceous shale, reducing construction costs, ensuring the quality of roadbed filling construction, and unifying and standardizing the technical standards for soft rock fillers as road fillers.

Description

Technical Field

[0001] The invention relates to the technical field of carbonaceous shale formation fillers for roads, and in particular to a method for screening carbonaceous shale formation fillers for roads. Background Art

[0002] With the rapid development of my country's transportation infrastructure, the construction mileage of roads and railways has been continuously refreshed, laying a solid foundation for the rapid development of my country's economy. Moreover, the construction of transportation infrastructure, whether roads or railways, is inseparable from filling construction.

[0003] Carbonaceous shale is a soft rock with unfavorable geological characteristics such as fast weathering, low strength, easy disintegration and softening when exposed to water. Compared with hard rock, it has low uniaxial compressive strength, strong water sensitivity, easy weathering, high compressibility, and low permeability, which makes it not an ideal roadbed filler. Carbonaceous shale is filled according to the construction method of general geological fillers. After the roadbed is opened to traffic, under the influence of vehicle loads and natural conditions, many diseases and problems will occur, such as uneven road surface settlement, embankment slope collapse, road surface cracks, etc., resulting in the deterioration of the roadbed structure and an increase in the amount of operation and maintenance engineering. In the early stage of railway and highway construction, this type of geology was generally bypassed when selecting the route. In recent years, due to the rapid development of my country's transportation network, the improvement of construction technology measures, and the urgent demand for environmental protection, the study of the road performance of soft rock fillers has become an issue that engineering and technical personnel and academia cannot avoid.

[0004] Therefore, in order to meet the urgent requirements of environmental protection and unify and standardize the technical standards for soft rock fillers as road fillers, a method for screening road carbonaceous shale formation fillers is urgently needed to screen out road carbonaceous shale formation fillers that meet the use requirements. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for screening carbonaceous shale formation fillers for roads, aiming to solve the urgent requirements of the prior art to meet environmental protection, and to unify and standardize the technical standards for soft rock fillers as road fillers. A method for screening carbonaceous shale formation fillers for roads is urgently needed to screen out technical problems of carbonaceous shale formation fillers for roads that meet the use requirements.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for screening road-use carbonaceous shale formation filler, wherein the carbonaceous shale formation comprises a plurality of sections of original carbonaceous shale filler, and the method comprises:

[0008] Collecting physical properties of the original carbonaceous shale filler in each section;

[0009] The physical properties of the original carbonaceous shale filler of each section are compared with the first preset condition respectively, and the original carbonaceous shale filler of each section that meets the first preset condition is used as each pre-screened carbonaceous shale filler;

[0010] Performing filler particle size analysis on each of the preliminarily screened carbonaceous shale fillers to obtain a filler particle size analysis result;

[0011] Classifying the primary screened carbonaceous shale fillers according to the particle size analysis results of the fillers to obtain secondary screened carbonaceous shale fillers;

[0012] Conducting a load ratio test on each of the two-sieve carbonaceous shale fillers to obtain the load ratio of each of the two-sieve carbonaceous shale fillers;

[0013] Compare the bearing ratio of each of the two-screened carbonaceous shale fillers with the second preset condition respectively, and use each of the two-screened carbonaceous shale fillers that meets the second preset condition as each of the three-screened carbonaceous shale fillers;

[0014] Conducting a confined compression test on each of the three-sieve carbonaceous shale fillers to obtain a compression coefficient of each of the three-sieve carbonaceous shale fillers;

[0015] Conducting a triaxial consolidation undrained test on each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers;

[0016] According to the compression coefficient of each of the three-sieve carbonaceous shale fillers and the water sensitivity of each of the three-sieve carbonaceous shale fillers, a road-use carbonaceous shale formation filler matching the corresponding roadbed is obtained.

[0017] Optionally, in the above-mentioned method for screening road carbonaceous shale formation filler, the step of collecting the physical properties of the original carbonaceous shale filler of each section includes:

[0018] The specific gravity of the soil particles of the original carbonaceous shale filler in each section is obtained by using a pycnometer method;

[0019] The moisture content of the original carbonaceous shale filler in each section is obtained by a drying method;

[0020] The liquid limit and plastic limit and plasticity index of the original carbonaceous shale filler in each section are obtained by using the liquid limit and plastic limit combined determination method;

[0021] The maximum dry density and the optimum moisture content of the original carbonaceous shale filler in each section are obtained by heavy compaction method.

[0022] Optionally, in the above-mentioned method for screening carbonaceous shale formation filler for road use, the first preset condition includes a liquid limit with a limit value of 50% and a plasticity index with an index value of 26;

[0023] The step of comparing the physical properties of the original carbonaceous shale filler of each section with the first preset condition and using the original carbonaceous shale filler of each section that meets the first preset condition as each pre-screened carbonaceous shale filler comprises:

[0024] The original carbonaceous shale fillers having a liquid limit less than or equal to 50% and a plasticity index less than or equal to 26 are used as primary screened carbonaceous shale fillers.

[0025] Optionally, in the above-mentioned method for screening carbonaceous shale formation fillers for road use, each of the initially screened carbonaceous shale fillers includes rock samples of different depths;

[0026] The step of performing filler particle size analysis on each of the preliminarily screened carbonaceous shale fillers to obtain the particle size analysis results of each filler comprises:

[0027] Mixing the rock samples at different depths in each of the initially screened carbonaceous shale fillers to obtain a mixed carbonaceous shale filler of each of the initially screened carbonaceous shale fillers;

[0028] The mixed carbonaceous shale filler of each of the initially screened carbonaceous shale fillers is sampled by using a quartering method;

[0029] The mixed carbonaceous shale fillers of each of the initially screened carbonaceous shale fillers are subjected to filler particle size analysis to obtain each of the filler particle size analysis results.

[0030] Optionally, in the above-mentioned method for screening road carbonaceous shale formation filler, the filler particle size analysis result includes an unevenness coefficient and a curvature coefficient, the value of the unevenness coefficient is Cu, and the value of the curvature coefficient is Cs;

[0031] The step of classifying each of the primary screened carbonaceous shale fillers according to the particle size analysis results of each of the fillers to obtain each of the secondary screened carbonaceous shale fillers comprises:

[0032] Each of the first-screened carbonaceous shale fillers with Cu>5 and 1<Cs<3 is used as each of the second-screened carbonaceous shale fillers.

[0033] Optionally, in the above-mentioned method for screening carbonaceous shale formation filler for road use, the minimum bearing ratio requirement of the roadbed filler is used as the second preset condition, and the value of the minimum bearing ratio is CBR;

[0034] The step of comparing the bearing ratio of each of the two-screened carbonaceous shale fillers with a second preset condition and using each of the two-screened carbonaceous shale fillers that meets the second preset condition as each of the three-screened carbonaceous shale fillers comprises:

[0035] The two-screen carbonaceous shale filler with 3%≤CBR is used as the three-screen carbonaceous shale filler.

[0036] Optionally, in the above-mentioned method for screening road carbonaceous shale formation fillers, the step of performing a confined compression test on each of the three-screened carbonaceous shale fillers to obtain the compression coefficient of each of the three-screened carbonaceous shale fillers includes:

[0037] The three-sieve carbonaceous shale fillers are pressurized in stages respectively;

[0038] When each stage of pressurization is completed, the stable deformation of each of the three-sieve carbonaceous shale fillers is collected;

[0039] According to each of the stable deformation amounts, a corresponding stable void ratio is calculated;

[0040] A compression curve is drawn with the void ratio as the ordinate and the pressure value of each level of pressurized load as the abscissa;

[0041] According to the compression curve, the compression coefficient of each of the three-sieve carbonaceous shale fillers is obtained.

[0042] Optionally, in the above-mentioned method for screening road carbonaceous shale formation fillers, the step of performing a triaxial consolidation undrained test on each of the three-screened carbonaceous shale fillers to obtain the water sensitivity of each of the three-screened carbonaceous shale fillers comprises:

[0043] Prepare samples of the three-sieve carbonaceous shale fillers to obtain dry samples of the three-sieve carbonaceous shale fillers;

[0044] A shear test is performed on the dry samples of each of the three-sieve carbonaceous shale fillers without adding water to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers.

[0045] Optionally, in the above-mentioned method for screening road carbonaceous shale formation fillers, the step of performing a triaxial consolidation undrained test on each of the three-screened carbonaceous shale fillers to obtain the water sensitivity of each of the three-screened carbonaceous shale fillers comprises:

[0046] Prepare samples of the three-sieve carbonaceous shale fillers to obtain dry samples of the three-sieve carbonaceous shale fillers;

[0047] Soaking the dried samples of the three-sieve carbonaceous shale fillers to obtain the water-soaked samples of the three-sieve carbonaceous shale fillers;

[0048] Pressurizing each of the three-sieve carbonaceous shale filler water-immersed samples to obtain each of the three-sieve carbonaceous shale filler water-immersed samples after pressurization;

[0049] A shear test is performed on the post-pressure water immersion samples of each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers.

[0050] Optionally, in the above-mentioned method for screening road carbonaceous shale formation fillers, the step of performing a triaxial consolidation undrained test on each of the three-screen carbonaceous shale fillers to obtain the water sensitivity of each of the three-screen carbonaceous shale fillers includes:

[0051] Prepare samples of the three-sieve carbonaceous shale fillers to obtain dry samples of the three-sieve carbonaceous shale fillers;

[0052] Applying different vertical pressures to the dried samples of the three-sieve carbonaceous shale fillers to obtain the pressed dried samples of the three-sieve carbonaceous shale fillers;

[0053] Soaking the dried samples of the three-sieve carbonaceous shale fillers after compression to obtain the water-soaked samples of the three-sieve carbonaceous shale fillers after compression;

[0054] A shear test is performed on the post-pressure water immersion samples of each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers.

[0055] The above one or more technical solutions provided by the present invention may have the following advantages or at least achieve the following technical effects:

[0056] The present invention proposes a method for screening carbonaceous shale formation fillers for roads. By conducting multiple tests on the original carbonaceous shale fillers of each section and testing and screening out carbonaceous shale formation fillers for roads that meet the use requirements according to the use requirements of the road fillers, the difficult problem that the roadbed of carbonaceous shale fillers is prone to various diseases is solved, the construction and utilization of carbonaceous shale is realized, the construction cost is reduced, and the quality of the roadbed filling construction is guaranteed. The long-term stability of the roadbed after opening to traffic is ensured, which accumulates valuable engineering experience for the design and construction of soft rock fillers in the future, and unifies and standardizes the technical standard requirements for soft rock fillers as road fillers. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0058] Figure 1 It is a schematic diagram of the process of the method for screening road-use carbonaceous shale formation filler of the present invention;

[0059] Figure 2 for Figure 1 A detailed flow chart of step S300;

[0060] Figure 3 for Figure 1A detailed flow chart of step S800 in the first embodiment;

[0061] Figure 4 for Figure 1 A detailed flow chart of the second embodiment of step S800;

[0062] Figure 5 for Figure 1 A detailed flow chart of step S800 in the third embodiment;

[0063] Figure 6 A reference table for the minimum bearing ratio requirements of the roadbed filler involved in the present invention;

[0064] Figure 7 It is a schematic diagram of the compression curve involved in the present invention.

[0065] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0067] Need to explain,

[0068] In the embodiment of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0069] In the present invention, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including 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 system. In the absence of further restrictions, an element defined by the sentence "includes..." does not exclude the presence of other identical elements in the process, method, article or system including the element. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B.

[0070] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixed", etc. should be understood in a broad sense. For example, "connection" 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; it can be the internal connection between two elements or the interaction relationship between two elements.

[0071] In the present invention, if there is a description involving "first", "second", etc., the description of "first", "second", etc. is only used for descriptive purposes and cannot be understood as indicating or implying its relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0072] In the present invention, suffixes such as "module", "component", "piece", "component" or "unit" used to represent elements are used only to facilitate the description of the present invention and have no specific meanings. Therefore, "module", "component" or "unit" may be used in a mixed manner.

[0073] For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical solutions of various embodiments can be combined with each other, but this is based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0074] The inventive concept of the present invention is further described below in conjunction with some specific implementation methods.

[0075] The invention provides a method for screening carbonaceous shale formation filler for roads.

[0076] Reference Figure 1 , Figure 1 It is a schematic diagram of the process of the method for screening road-use carbonaceous shale formation filler of the present invention.

[0077] In one embodiment of the present invention, Figure 1 As shown, the carbonaceous shale formation includes multiple sections of original carbonaceous shale fillers, and the method for screening road-use carbonaceous shale formation fillers includes:

[0078] S100: Collect the physical properties of the original carbonaceous shale filler in each section, and test the basic physical properties of the original carbonaceous shale filler in each section:

[0079] (1) Specific gravity of soil particles, measured by pycnometer method;

[0080] (2) The moisture content is tested by the drying method;

[0081] (3) Liquid limit and plastic limit and plasticity index, tested by the liquid limit and plastic limit combined determination method;

[0082] (4) The maximum dry density and optimum moisture content are tested using the heavy compaction method.

[0083] Through the above four groups of tests, the basic physical properties of the carbonaceous shale filler in each section are tested, which can be used to identify its road usability or as a quality standard for later construction.

[0084] S200: respectively comparing the physical properties of the original carbonaceous shale fillers of each section with the first preset condition, and taking the original carbonaceous shale fillers of each section that meet the first preset condition as each pre-screened carbonaceous shale filler, that is, through the liquid limit and plasticity index, screening out the original carbonaceous shale fillers that cannot be directly used for embankment filling, and taking the remaining original carbonaceous shale fillers as each pre-screened carbonaceous shale filler;

[0085] S300: performing filler particle size analysis on each of the preliminarily screened carbonaceous shale fillers to obtain a particle size analysis result of each filler;

[0086] S400: Classify each of the primary screened carbonaceous shale fillers according to the results of the particle size analysis of each of the fillers to obtain each secondary screened carbonaceous shale filler. The particle composition characteristics of the filler are a major factor affecting the engineering properties of the filler. The filler is classified according to the particle size gradation composition of the filler, and is used as an important basis for evaluating the engineering properties of the filler. The non-uniformity coefficient (Cu) and the curvature coefficient (Cs) are often used as two indicators to determine the particle size gradation of the filler. The primary screened carbonaceous shale filler is screened according to the non-uniformity coefficient (Cu) and the curvature coefficient (Cs) to obtain the secondary screened carbonaceous shale filler;

[0087] S500: performing a bearing ratio test on each of the two-sieve carbonaceous shale fillers to obtain the bearing ratio of each of the two-sieve carbonaceous shale fillers, wherein the bearing ratio is the minimum bearing ratio (CBR value), which refers to the ratio of the load applied by the standard specimen when the penetration amount is 2.5 mm to the load applied by the standard crushed stone material when the penetration amount is the same, expressed as a percentage;

[0088] S600: Compare the bearing ratio of each of the two-screened carbonaceous shale fillers with the second preset condition respectively. The CBR value of each of the two-screened carbonaceous shale fillers can reflect the local shear strength and water stability of the filler, which is the technical basis for ensuring that the filler soil structure is not destroyed when the roadbed is immersed in water for a long time, and is an important basis for selecting highway roadbed fillers. Whether carbonaceous shale can be used as filler for highway embankments must be studied by carrying out bearing ratio tests to determine whether its CBR value can meet road use requirements. Each of the two-screened carbonaceous shale fillers that meet the second preset condition is used as each of the three-screened carbonaceous shale fillers;

[0089] S700: performing a confined compression test on each of the three-sieve carbonaceous shale fillers to obtain a compression coefficient of each of the three-sieve carbonaceous shale fillers. Indoor compression test is the most basic method for studying the compressibility of fillers. Since only vertical compression deformation can occur during the compression process, and lateral deformation cannot occur, it is also called confined compression test.

[0090] S800: performing a triaxial consolidation undrained test on each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers. The triaxial consolidation undrained test has the advantages of being able to highly simulate the on-site conditions and fully reflect the test stress deformation until destruction. It can be used for both strength tests and stress-strain relationship tests. It is one of the basic geotechnical tests. The triaxial consolidation undrained test is used to detect the cohesion and friction angle of the on-site fillers respectively.

[0091] S900: Cohesion and friction angle are two indicators of the shear strength of the filler. The corresponding cohesion and internal friction angle of the filler are different at different dry densities. The influence of dry density on cohesion and internal friction angle has the following rule: with the increase of dry density, that is, the gradual increase of compaction degree, cohesion and internal friction angle both gradually increase, that is, the shear strength of the filler is gradually increasing; when the dry density is relatively small, with the gradual increase of dry density, the growth rate of cohesion and friction angle is relatively slow. When the dry density increases to a certain value, with the continued increase of dry density, the growth rate of cohesion and friction angle accelerates; when the dry density continues to increase to a range of values, the growth rate of cohesion and friction angle gradually decreases with the increase of dry density. Therefore, according to the compression coefficient of each of the three-sieve carbonaceous shale fillers and the water sensitivity of each of the three-sieve carbonaceous shale fillers, a road-use carbonaceous shale formation filler matching the corresponding roadbed is obtained.

[0092] Although carbonaceous shale has unfavorable geological characteristics such as fast weathering, low strength, and easy disintegration when exposed to water, which makes it difficult to become an ideal roadbed filler, if it is abandoned, it will not only increase the cost of the project, but also occupy a large amount of land and pollute the environment. In addition, due to the inability of plants to grow in carbonaceous shale, the carbonaceous shale dump will become a barren land, which not only occupies a large amount of land in mountainous areas where land is extremely scarce, but also the high carbonaceous shale dump will eventually silt up streams and rivers due to the long-term weathering and disintegration of rocks and the continuous scouring of rainwater. At the same time, geological disasters such as mudslides and collapses may occur during the rainy season, threatening the lives and property of the people, and is not conducive to saving land resources and protecting the environment, and violates the strategy of "good and fast" economic development in my country.

[0093] However, the application and promotion of this method can solve or reduce the occurrence of the above problems and play a positive role in promoting environmental protection policies.

[0094] The technical solution of the present invention conducts multiple tests on the original carbonaceous shale filler of each section, and tests and screens out carbonaceous shale formation fillers for roads that meet the use requirements according to the use requirements of road fillers, thereby solving the difficult problem that various diseases are prone to occur in the roadbed of carbonaceous shale fillers, realizing the construction and utilization of carbonaceous shale, reducing construction costs, and ensuring the quality of roadbed filling construction. The long-term stability of the roadbed after opening to traffic has accumulated valuable engineering experience for the design and construction of soft rock fillers in the future, and unified and standardized the technical standard requirements for soft rock fillers as road fillers.

[0095] In one embodiment, the step of collecting the physical properties of the original carbonaceous shale filler in each section includes:

[0096] S110: using a pycnometer method to obtain the soil particle specific gravity of the original carbonaceous shale filler in each section;

[0097] S120: obtaining the moisture content of the original carbonaceous shale filler in each section by a drying method;

[0098] S130: using a liquid-plastic limit combined determination method to obtain the liquid-plastic limit and plastic index of the original carbonaceous shale filler in each section;

[0099] S140: A heavy compaction method is used to obtain the maximum dry density and optimum moisture content of the original carbonaceous shale filler in each section, so as to obtain various physical properties of the original carbonaceous shale filler through steps S110 to S140, and the obtained various physical properties are used as screening criteria for the original carbonaceous shale filler to obtain a pre-screened carbonaceous shale filler that meets the use requirements.

[0100] In one embodiment, the first preset condition includes a liquid-plastic limit with a limit value of 50% and a plasticity index with an index value of 26;

[0101] The step of comparing the physical properties of the original carbonaceous shale filler of each section with the first preset condition and using the original carbonaceous shale filler of each section that meets the first preset condition as each pre-screened carbonaceous shale filler comprises:

[0102] S210: taking the original carbonaceous shale fillers having a liquid limit less than or equal to 50% and a plasticity index less than or equal to 26 as primary screened carbonaceous shale fillers.

[0103] Continue to refer to Figure 1 , and refer to Figure 2 , Figure 2 for Figure 1 Detailed flowchart of step S300.

[0104] In one embodiment of the present invention, Figure 1 and Figure 2As shown in the figure, in complex strata, it is basically impossible to accurately grasp the index characteristics of representative samples due to the influence of sampling location, sample burial depth, weathering degree, occurrence, mining method, parent rock properties and types, and different atmospheric environments after the filler is excavated. Considering that the particle sizes of carbonaceous shale at different depths and different weathering degrees vary greatly, which has a serious impact on soil particle indicators, before the test, the fillers of each section are mixed together, and then the quartering method is used for sampling, and finally the sample is used for particle size analysis test.

[0105] Specifically, each of the initially screened carbonaceous shale fillers includes rock samples of different depths, and the step of performing filler particle size analysis on each of the initially screened carbonaceous shale fillers to obtain the particle size analysis results of each filler includes:

[0106] S310: mixing the rock samples at different depths in the initially screened carbonaceous shale fillers to obtain mixed carbonaceous shale fillers of the initially screened carbonaceous shale fillers;

[0107] S320: sampling the mixed carbonaceous shale fillers of each of the preliminarily screened carbonaceous shale fillers by using a quartering method;

[0108] S330: performing filler particle size analysis on the mixed carbonaceous shale fillers of each of the initially screened carbonaceous shale fillers to obtain the filler particle size analysis results.

[0109] In one embodiment, the filler particle size analysis result includes a non-uniformity coefficient and a curvature coefficient, the non-uniformity coefficient is Cu, and the curvature coefficient is Cs;

[0110] The particle composition characteristics of the filler are a major factor affecting the engineering properties of the filler. A good filler gradation needs to meet the following requirements at the same time: the uniformity coefficient Cu>5, the curvature coefficient 1<Cs<3.

[0111] Therefore, the step of classifying each of the primary screened carbonaceous shale fillers according to the particle size analysis results of each of the fillers to obtain each of the secondary screened carbonaceous shale fillers includes:

[0112] S510: using the first-screened carbonaceous shale fillers with Cu>5 and 1<Cs<3 as the second-screened carbonaceous shale fillers.

[0113] In one embodiment, the minimum bearing ratio requirement of the roadbed filler is used as the second preset condition, and the value of the minimum bearing ratio is CBR;

[0114] S610: The step of comparing the bearing ratio of each of the two-screened carbonaceous shale fillers with a second preset condition and using each of the two-screened carbonaceous shale fillers that meets the second preset condition as each of the three-screened carbonaceous shale fillers comprises:

[0115] S620: Use the second-screen carbonaceous shale filler with 3%≤CBR as the third-screen carbonaceous shale filler.

[0116] Specifically, the CBR value of the filler can reflect the local shear strength and water stability of the filler. It is the technical basis for ensuring that the filler soil structure is not destroyed when the roadbed is immersed in water for a long time, and it is an important basis for the selection of highway roadbed fillers. Whether carbonaceous shale can be used as filler for highway embankments must be studied by carrying out bearing ratio tests to determine whether its CBR value can meet road use requirements.

[0117] Reference Figure 6 , Figure 6 This is a reference table for the minimum bearing ratio requirements of the roadbed filler involved in the present invention. Figure 6 Refer to the table for minimum bearing ratio requirements for roadbed fillers shown in the figure to obtain three-sieve carbonaceous shale fillers that match the filler application site (depth below the bottom of the road surface), i.e., the corresponding roadbed.

[0118] In one embodiment, the step of performing a confined compression test on each of the three-sieve carbonaceous shale fillers to obtain the compression coefficient of each of the three-sieve carbonaceous shale fillers comprises:

[0119] S710: Pressurizing the three-sieve carbonaceous shale fillers in different grades respectively;

[0120] S720: During the test, the pressure is gradually and evenly applied to the sample through the loading device. After each level of load is applied, the next level of load is applied after the test compression is stable. The compression amount of the sample is measured by the displacement sensor. When each level of pressurization is completed, the stable deformation amount of each of the three sieve carbonaceous shale fillers is collected;

[0121] S730: Calculating a corresponding stable void ratio according to each of the stable deformation amounts;

[0122] S740: using the porosity ratio as the ordinate and the pressure value of each level of pressurized load as the abscissa, a porosity ratio and pressure relationship curve is drawn according to the compression test, that is, a compression curve is drawn;

[0123] S750: Obtaining the compression coefficient of each of the three-sieve carbonaceous shale fillers according to the compression curve.

[0124] Specifically, the shape of the compression curve is related to the composition, structure, state and stress duration of the sample. The steeper the compression curve, the more the porosity decreases when the pressure increases, the easier the sample soil is to deform, and the higher the compressibility; otherwise, the sample is not easy to deform, and the compressibility of the sample soil is relatively low. The slope of the compression curve can vividly illustrate the compressibility of the soil.

[0125] like Figure 7 As shown, Figure 7This is a schematic diagram of the compression curve involved in the present invention. Assume that the soil pressure increases from P1 to P2, and the corresponding porosity decreases from e1 to e2. When the pressure change range is not large, the small section of the curve M1M2 can be replaced by a secant line, and the slope of the secant line M1M2 is used to represent the compressibility of the sample in this pressure range, that is: α=tanα=(e1-e2) / (P1-P2)=△e / △p; This formula is one of the basic laws of the mechanical properties of soil, the compression law. α is called the compression coefficient, which is an important indicator to characterize the compressibility of soil. The larger its value, the higher the compressibility of the soil. The compression coefficient α is related to the load on the soil. Generally, when the pressure interval P1=100KPa and P2=200KPa is used, the corresponding compression coefficient α 1-2 To evaluate the compressibility of soil: when α 1-2 <0.1MPa -1 When 0.1MPa, it is low compressibility soil; -1 ≤α 1-2 <0.5MPa -1 When α 1-2 ≥0.5MPa -1 It is a highly compressible soil.

[0126] According to the results of on-site sampling and indoor test, the compression coefficient of the carbonaceous shale filler in this project is: α 1-2 At 0.1MPa -1 To 0.5MPa -1 It is a medium compressible filler.

[0127] Continue to refer to Figure 1 , and refer to Figure 3 , Figure 3 for Figure 1 FIG. 5 is a schematic diagram of a detailed flow chart of the first embodiment of step S800.

[0128] In one embodiment of the present invention, Figure 1 and Figure 3 As shown, the steps of performing a triaxial consolidation undrained test on each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers include:

[0129] S810a: preparing samples of the three-sieve carbonaceous shale fillers to obtain dry samples of the three-sieve carbonaceous shale fillers;

[0130] S820a: Perform a shear test on the dry samples of each of the three-sieve carbonaceous shale fillers without adding water to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers.

[0131] Taking into account the influence of water on carbonaceous shale filler, a shear test was carried out on the dry sample of the three-sieve carbonaceous shale filler without adding water to obtain the consolidated undrained shear strength of the dry sample, so as to determine whether the three-sieve carbonaceous shale filler can be used as road filler in a dry condition.

[0132] Specifically, the water sensitivity in this scheme refers to the phenomenon that when fresh water enters the carbonaceous shale filler, the carbonaceous shale filler will expand, resulting in a decrease in permeability.

[0133] Continue to refer to Figure 1 , and refer to Figure 4 , Figure 4 for Figure 1 FIG. 5 is a schematic diagram of a detailed flow chart of the second embodiment of step S800.

[0134] In one embodiment of the present invention, Figure 1 and Figure 4 As shown, the steps of performing a triaxial consolidation undrained test on each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers include:

[0135] S810b: preparing samples of the three-sieve carbonaceous shale fillers to obtain dry samples of the three-sieve carbonaceous shale fillers;

[0136] S820b: soaking the dry samples of the three-sieve carbonaceous shale fillers to obtain water-soaked samples of the three-sieve carbonaceous shale fillers;

[0137] S830b: pressurizing each of the three-sieve carbonaceous shale filler water-immersed samples to obtain each of the three-sieve carbonaceous shale filler water-immersed samples after pressurization;

[0138] S840b: Perform a shear test on the post-pressure water immersion samples of each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers.

[0139] Taking into account the influence of water on carbonaceous shale filler, a shear test was carried out on the three-sieve carbonaceous shale filler's water-immersed sample after pressure testing to obtain the consolidated undrained shear strength of the three-sieve carbonaceous shale filler's water-immersed sample after pressure testing, so as to determine whether the three-sieve carbonaceous shale filler's water-immersed sample after pressure testing can be used as road filler.

[0140] Continue to refer to Figure 1 , and refer to Figure 5 , Figure 5 for Figure 1 FIG. 5 is a schematic diagram of a detailed flow chart of step S800 in the third embodiment.

[0141] In one embodiment of the present invention, Figure 1 and Figure 5As shown, the steps of performing a triaxial consolidation undrained test on each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers include:

[0142] S810c: preparing samples of the three-sieve carbonaceous shale fillers to obtain dry samples of the three-sieve carbonaceous shale fillers;

[0143] S820c: applying different vertical pressures to the dried samples of the three-sieve carbonaceous shale fillers to obtain the dried samples of the three-sieve carbonaceous shale fillers after pressure;

[0144] S830c: soaking the dried samples of the three-sieve carbonaceous shale fillers after compression to obtain the water-soaked samples of the three-sieve carbonaceous shale fillers after compression;

[0145] S840c: Perform a shear test on the post-pressure immersion samples of each of the three-sieve carbonaceous shale fillers to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers.

[0146] Since carbonaceous shale fillers are highly water sensitive, their shear strength will decrease rapidly when exposed to water. The above three embodiments of conducting triaxial consolidation undrained tests on the three-sieve carbonaceous shale fillers to obtain the water sensitivity of the three-sieve carbonaceous shale fillers are to screen out the different water immersion states of the same section of soil samples under three soil sample states, and are mainly used to obtain the water sensitivity of carbonaceous shale fillers, and select each carbonaceous shale filler that meets the target water sensitivity according to the needs of matching the roadbed.

[0147] For ease of understanding, a specific implementation is shown here:

[0148] In a certain project, the above-mentioned S800 step test showed that when the filler compaction degree at K75+630 was 96%, its consolidated undrained shear strength index Ccu was 32.4kPa, and ψcu was 30.48°; when the filler compaction degree at K78+230 was 96%, its consolidated undrained shear strength index Ccu was 28.9kPa, and ψcu was 32.5°; when the filler compaction degree at K80+980 was 96%, its consolidated undrained shear strength index Ccu was 25.59kPa, and ψcu was 27.6°; when the filler compaction degree at K82+220 was 96%, its consolidated undrained shear strength index Ccu was 22.36kPa, and ψcu was 26.93°.

[0149] The test results show that the consolidated undrained shear strength of the dry sample is relatively large, while the cohesion and internal friction angle of the immersed sample are greatly weakened, indicating that the strength of carbonaceous shale filler is sensitive to water. Therefore, during the embankment construction process, more attention should be paid to strengthening underground drainage to prevent the roadbed from being flooded, and at the same time prevent the cracking of the road surface from causing surface water infiltration to reduce the roadbed settlement.

[0150] It should be noted that the serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments. The above embodiments are only optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structures or equivalent process changes made by using the contents of the present specification and drawings under the inventive concept of the present invention, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for screening carbonaceous shale formation filler for road use, characterized in that: The carbonaceous shale formation includes a plurality of sections of original carbonaceous shale filler, and the method includes: Collecting physical properties of the original carbonaceous shale filler in each section; The physical properties of the original carbonaceous shale filler of each section are compared with the first preset condition respectively, and the original carbonaceous shale filler of each section that meets the first preset condition is used as each pre-screened carbonaceous shale filler; Performing filler particle size analysis on each of the preliminarily screened carbonaceous shale fillers to obtain a filler particle size analysis result; Classifying the primary screened carbonaceous shale fillers according to the particle size analysis results of the fillers to obtain secondary screened carbonaceous shale fillers; Conducting a load ratio test on each of the two-sieve carbonaceous shale fillers to obtain the load ratio of each of the two-sieve carbonaceous shale fillers; Compare the bearing ratio of each of the two-screened carbonaceous shale fillers with the second preset condition respectively, and use each of the two-screened carbonaceous shale fillers that meets the second preset condition as each of the three-screened carbonaceous shale fillers; Conducting a confined compression test on each of the three-sieve carbonaceous shale fillers to obtain a compression coefficient of each of the three-sieve carbonaceous shale fillers; Prepare samples of the three-sieve carbonaceous shale fillers to obtain dry samples of the three-sieve carbonaceous shale fillers; Conducting a shear test on the dry samples of each of the three-sieve carbonaceous shale fillers without adding water to obtain the water sensitivity of each of the three-sieve carbonaceous shale fillers; According to the compression coefficient of each of the three-sieve carbonaceous shale fillers and the water sensitivity of each of the three-sieve carbonaceous shale fillers, a road-use carbonaceous shale formation filler matching the corresponding roadbed is obtained.

2. The method for screening road carbonaceous shale formation filler according to claim 1, characterized in that: The step of collecting the physical properties of the original carbonaceous shale filler in each section includes: The specific gravity of the soil particles of the original carbonaceous shale filler in each section is obtained by using a pycnometer method; The moisture content of the original carbonaceous shale filler in each section is obtained by a drying method; The liquid limit and plastic limit and plasticity index of the original carbonaceous shale filler in each section are obtained by using the liquid limit and plastic limit combined determination method; The maximum dry density and the optimum moisture content of the original carbonaceous shale filler in each section are obtained by heavy compaction method.

3. The method for selecting road carbonaceous shale formation filler according to claim 2, characterized in that: The first preset condition includes a liquid-plastic limit with a limit value of 50% and a plasticity index with an index value of 26; The step of comparing the physical properties of the original carbonaceous shale filler of each section with the first preset condition and using the original carbonaceous shale filler of each section that meets the first preset condition as each pre-screened carbonaceous shale filler comprises: The original carbonaceous shale fillers having a liquid limit less than or equal to 50% and a plasticity index less than or equal to 26 are used as primary screened carbonaceous shale fillers.

4. The method for screening road carbonaceous shale formation filler according to claim 3, characterized in that: Each of the initially screened carbonaceous shale fillers includes rock samples of different depths; The step of performing filler particle size analysis on each of the preliminarily screened carbonaceous shale fillers to obtain the particle size analysis results of each filler comprises: Mixing the rock samples at different depths in each of the initially screened carbonaceous shale fillers to obtain a mixed carbonaceous shale filler of each of the initially screened carbonaceous shale fillers; The mixed carbonaceous shale filler of each of the initially screened carbonaceous shale fillers is sampled by using a quartering method; The mixed carbonaceous shale fillers of each of the initially screened carbonaceous shale fillers are subjected to filler particle size analysis to obtain each of the filler particle size analysis results.

5. The method for screening road carbonaceous shale formation filler according to claim 4, characterized in that: The filler particle size analysis result includes an unevenness coefficient and a curvature coefficient, the value of the unevenness coefficient is Cu, and the value of the curvature coefficient is Cs; The step of classifying each of the primary screened carbonaceous shale fillers according to the particle size analysis results of each of the fillers to obtain each of the secondary screened carbonaceous shale fillers comprises: Each of the first-screened carbonaceous shale fillers with Cu>5 and 1<Cs<3 is used as each of the second-screened carbonaceous shale fillers.

6. The method for screening road carbonaceous shale formation filler according to claim 5, characterized in that: The minimum bearing ratio requirement of the roadbed filler is used as the second preset condition, and the value of the minimum bearing ratio is CBR; The step of comparing the bearing ratio of each of the two-screened carbonaceous shale fillers with a second preset condition and using each of the two-screened carbonaceous shale fillers that meets the second preset condition as each of the three-screened carbonaceous shale fillers comprises: The two-screen carbonaceous shale filler with 3%≤CBR is used as the three-screen carbonaceous shale filler.

7. The method for screening road carbonaceous shale formation filler according to any one of claims 1 to 6, characterized in that: The step of performing a confined compression test on each of the three-sieve carbonaceous shale fillers to obtain the compression coefficient of each of the three-sieve carbonaceous shale fillers comprises: The three-sieve carbonaceous shale fillers are pressurized in stages respectively; When each stage of pressurization is completed, the stable deformation of each of the three-sieve carbonaceous shale fillers is collected; According to each of the stable deformation amounts, a corresponding stable void ratio is calculated; A compression curve is drawn with the void ratio as the ordinate and the pressure value of each level of pressurized load as the abscissa; According to the compression curve, the compression coefficient of each of the three-sieve carbonaceous shale fillers is obtained.

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