CN104895017A - Pore distribution index based cushion material grading design optimization method for cold regions - Google Patents

Pore distribution index based cushion material grading design optimization method for cold regions Download PDF

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Publication number
CN104895017A
CN104895017A CN201510254186.8A CN201510254186A CN104895017A CN 104895017 A CN104895017 A CN 104895017A CN 201510254186 A CN201510254186 A CN 201510254186A CN 104895017 A CN104895017 A CN 104895017A
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pores
distribution
index
bedding material
fine sand
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CN104895017B (en
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袁俊平
王强林
韩春雷
李康波
丁国权
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Hohai University HHU
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Hohai University HHU
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Abstract

The invention discloses a pore distribution index based cushion material grading design optimization method for cold regions. The method is characterized by comprising the steps of S01, rolling density determination; S02, replacing of clay particles by fine sand groups; S03, pore distribution index determination; S04, grading adjustment. By the aid of the method, the grading selection range is reduced, the experiment workload is reduced, the requirements for the compactness deserved by serving as face slab support materials and permeability that shall be possessed by draining water leaking into the cushion materials of the cushion materials are met, the cushion material frost heaving deformation in condition of freezing and thawing cycle is the smallest, and the produced frost heaving deformation cannot affect the normal use of concrete face dams under the constraint of vertical pressure of the concrete face dams.

Description

Cold district is based on the bedding material gradation design optimization method of distribution of pores index
Technical field
The present invention relates to the bedding material gradation design optimization method of a kind of cold district based on distribution of pores index, belong to hydraulic engineering, highway engineering field.
Background technology
In hydraulic engineering, Concrete Face Rockfill Dam to receive the favor of engineer because of its good compliance in west area, much built and have employed this dam type at the dam of founding a capital.But due to western frozen soil characteristic and climate reasons, if the water entering bed course can not be discharged in time, local frost heave may be produced, cause face dam to produce inhomogeneous deformation cracking, and then affect the stable of dam body.Bedding material frost-heaving deformation is relevant with grating with its permeability, and choosing of rational gradation composition becomes most important for control pad layered material frost-heaving deformation.
The difference of grating, causes the difference of bedding material distribution of pores, and under cold conditions, water enters the soil body and can not discharge in time, and water-cooled freezes the long-pending increase of ice body, oppresses soil body hole and causes body frost heaving.Therefore body frost heaving and the distribution of the soil body when mesopore have close contacting.
Summary of the invention
Technical problem to be solved by this invention is, a kind of range of choice optimizing grating is provided, reduce experiment work amount, determine bedding material as the due compactness of panel support material and discharging leak in bedding material water this have infiltrative while, ensure that the frost-heaving deformation of Frozen-thawed cycled strength condition underlay layered material is minimum, and the frost-heaving deformation produced can not affect the bedding material gradation design optimization method of cold district based on distribution of pores index of the normal use of face dam under the pressure at right angle constraint of face dam.
For solving the problems of the technologies described above, the technical solution used in the present invention is:
Cold district, based on the bedding material gradation design optimization method of distribution of pores index, is characterized in that: comprise the following steps:
S01, rolls the determination of density: the density design that rolls of bedding material is 0.75 ~ 0.80, to make the existing higher relative density of bedding material, does not produce larger frost-heaving deformation again;
S02, fine sand group replaces powder clay: the fine sand grain diameter replaced in the fine sand group of powder clay is 0.075 ~ 0.6mm, and other gratings are with thanking to rad grating;
S03, the determination of distribution of pores index: in bedding material, the distribution of pores index of each group grating is-6.3 ~-6.2;
S04, gradation adjustment: carry out frost heave and infiltration test, whether test sample frozen-heave factor, transmission coefficient meet engine request; If sample transmission coefficient is excessive, then distribution of pores index should tune up in above-mentioned number range; If transmission coefficient is too small or frozen-heave factor is excessive, then distribution of pores index should be turned down in above-mentioned number range; Adjustment is until reasonably grating appearance.
Described grating comprises described fine sand group and particle diameter is 80 ~ 100mm coarse gravel group; Described grating is continuous grading; Suppose that the particle size in each grating is consistent, be the arithmetic mean of instantaneous value of maximum particle diameter and minimum grain size; Suppose that the particle in each grating is spherical and is uniformly distributed.
The described density that rolls is preferably 0.78 ~ 0.80.
Fine sand grain diameter in described fine sand group is 0.07 ~ 0.6mm.
Fine sand grain diameter in described fine sand group is 0.065 ~ 0.6mm.
Described distribution of pores index is-6.25 ~-6.2.
Described distribution of pores index is-6.3 ~-6.25.
The content range of described fine sand group shared by all gratings is 3.75 ~ 8.75%.
The content range of described fine sand group shared by all gratings is 4 ~ 8%.
The difference of grating, causes the difference of bedding material distribution of pores, and under cold conditions, water enters the soil body and can not discharge in time, and water-cooled freezes the long-pending increase of ice body, oppresses soil body hole and causes body frost heaving.Therefore body frost heaving and the distribution of the soil body when mesopore have close contacting.Based on this, propose the concept of distribution of pores model, simulate the true distribution of soil body mesopore with distribution of pores model.
Distribution of pores model assumption:
1) particle is ideal ball body;
2) different size particles is uniformly distributed completely;
3) same grain group particle size is consistent, is the arithmetic mean of instantaneous value of this group maximum particle diameter and minimum grain size;
4) appoint and get the certain volume soil body, its void ratio remains unchanged, and namely soil body mesopore is uniformly distributed completely.
Like this, the average grain volume size v of each grain group in the unit mass soil body can be calculated iwith total number of particles n ifor:
v i = 1 6 π d i 3 - - - ( 1 )
n i = m i v i ρ si - - - ( 2 )
In formula (1)-(2): v iit is average grain volume in i-th grain group; n iit is the total number of particles of i-th grain group; m ifor the quality of i-th grain group in the unit quality soil body; d iit is the average diameter (arithmetic mean of instantaneous value) of i-th grain group; ρ sibe i-th grain group particle mean specific gravity; E is sample void ratio.
For supposition 4), the corresponding voids volume of each soil particle, and the voids volume (hereinafter referred to as equivalent voids volume) that each particle occupies can be calculated be:
e = v i ′ v i - - - ( 3 )
d ′ = 6 v i ′ π 3 - - - ( 4 )
In formula (3)-(4): e is sample void ratio; V' iit is the equivalent voids volume in i-th grain group; D' is equivalent pore diameter.
Space profile exponent (PDI) is a parameter of the quantitative study soil mesopore distribution put forward based on above-mentioned hole distributed model.Distribution of pores index (PDI) design formulas is as follows:
PDI = Σlg ( d 0 d ) lg n - - - ( 5 )
In formula (5): n is equivalent hole quantity in a certain grain group; D is the diameter of equivalent hole in a certain grain group; d 0for critical equivalent pore diameter, d 0=0.118mm;
In soil, fine pore accounts for leading, then PDI value is large; In soil, macrovoid accounts for leading, then PDI value is little.
The present invention be directed to bedding material frost-heaving deformation and a kind of cold district proposed based on the bedding material gradation design optimization method of distribution of pores index, present invention employs following technical scheme:
Roll density to determine: for making the existing higher relative density of bedding material, do not produce larger frost-heaving deformation again, suggestion bedding material relative density scope is designed to 0.75 ~ 0.80.
Clay replacement method: do not affecting in infiltrative situation, in the bedding material design of suggestion cold district, the content of powder clay is substituted by fine sand group particle (0.075 ~ 0.6mm), and other groups are with reference to thanking to rad grating.
Distribution of pores index range is selected: each group grating can by calculating the distribution of pores index of self, and the scope of the distribution of pores index of the grating after suggestion powder clay is replaced is-6.3 ~-6.2.Therefore engineering is selected level timing maiden trial grating can select within the scope of this, for selecting rational gradation composition to reduce range of choice, decrease experiment work amount.
Gradation adjustment measure: after choosing grating by said method, carry out frost heave, infiltration test by method for normalizing, whether test sample frozen-heave factor, transmission coefficient meet engine request.If test transmission coefficient is excessive, then distribution of pores index should tune up in suggested range; If transmission coefficient is too small or frozen-heave factor is excessive, then distribution of pores index should be turned down in suggested range; Adjustment is until reasonably grating appearance.
Advantage of the present invention is: reduce grating selection range, decrease experiment work amount, meet bedding material and leak this permeability had of water in bedding material as the due compactness of panel support material and discharge, ensure that the frost-heaving deformation of Frozen-thawed cycled strength condition underlay layered material is minimum, and the frost-heaving deformation produced can not affect the normal use of face dam under the pressure at right angle constraint of face dam simultaneously.
Accompanying drawing explanation
Fig. 1 is the structural representation of face dam in the present invention;
Fig. 2 is bedding material frost heave relative density suggested range figure;
Fig. 3 is bedding material frost heaving amount and powder clay content graph of a relation;
Fig. 4 is that fine sand grain replaces powder clay content suggested range figure;
Hole profile exponent suggested range figure when Fig. 5 is frost-heaving deformation;
Hole profile exponent suggested range figure when Fig. 6 is angle of friction;
Fig. 7 is suggestion grating schematic diagram (suggestion grating have references to international recommendation grating-Xie rad grating).
Detailed description of the invention
Below in conjunction with accompanying drawing, the present invention is further described.
Embodiment 1:
As shown in Fig. 1 ~ 7, cold district, based on the bedding material gradation design optimization method of distribution of pores index, is characterized in that: comprise the following steps:
S01, rolls density and determines:
As shown in Figure 1, be the position of bedding material in face dam, it is to the requirement of relative density, and Concrete Face Rockfill Dam design specifications requires more than 0.75.
As shown in Figure 2, the rule that under freeze-thaw cycles, frost heave test draws is: bedding material relative density is larger, and frost-heaving deformation is larger.For making the existing higher relative density of bedding material, do not produce larger frost-heaving deformation again, suggestion bedding material relative density scope is designed to 0.75 ~ 0.80.
S02, clay replacement method:
As shown in Figure 3, to the requirement of clay content, the granule content that specifications recommend is less than 0.075mm should be less than 8%.Lot of documents research proves that in bedding material, clay content is more, and frost heaving amount is larger, has the rule similar to powder clay when finding that 0.075 ~ 0.6mm fine content is more in experimental study on the impact of frost-heaving deformation.
As shown in Figure 4, when the granule content of fine sand is in a certain scope (3.75% ~ 8.75%), less on the impact of frost-heaving deformation, therefore, do not affecting in infiltrative situation, in the bedding material design of suggestion cold district, the content of powder clay is 3.75% and is substituted by this group particle (0.075 ~ 0.6mm).
As shown in Figure 7, other groups are with reference to thanking to rad grating.
S03, distribution of pores index range is selected:
To the requirement of grating, specifications recommend bedding material grating should be continuous, and maximum particle diameter is 80 ~ 100mm, the granule content that particle diameter is less than 5mm is preferably 30% ~ 50%, should have internal penetration stability, low compressibility after compacting, high shear strength, and good construction property should be had.Each group grating can by calculating the distribution of pores index of self, and test finds that distribution of pores index reflects frost-heaving deformation and intensity (angle of friction and the cohesion) Changing Pattern of bedding material.
As shown in Figure 6, along with the increase of distribution of pores index, frost-heaving deformation increases gradually, and angle of friction is the parabola change of opening upwards.Though bedding material has the powder clay of certain content, primarily of sand gravel composition, belong to dispersed material, the impact of cohesion during bedding material design, can be ignored.
As shown in Figure 5, for making bedding material distortion when frost heave less, suggestion distribution of pores Index selection scope is-6.4 ~-6.2.As shown in Figure 6, freeze thawing distortion can produce Particle Breakage, thus changes the grating of particle, for making the angle of friction of bedding material still safety when grain composition changes, advises that distribution of pores Index selection scope is-6.3 ~-6.1.Consider, the scope of suggestion distribution of pores index is-6.3 ~-6.2.
Rational gradation composition range reference Fig. 7 of distribution of pores index conversion.
Therefore engineering is selected level timing maiden trial grating can select within the scope of this, for selecting rational gradation composition to reduce range of choice, decrease experiment work amount.
S04, gradation adjustment measure:
After choosing grating by said method, carry out frost heave, infiltration test by method for normalizing, whether test sample frozen-heave factor, transmission coefficient meet engine request.If test transmission coefficient is excessive, then distribution of pores index should tune up in suggested range; If transmission coefficient is too small or frozen-heave factor is excessive, then distribution of pores index should be turned down in suggested range; Adjustment is until reasonably grating appearance.
Preferably, the density design that rolls of bedding material is 0.75; The fine sand grain diameter replaced in the fine sand group of powder clay is 0.075mm, and other gratings are with thanking to rad grating; In bedding material, the distribution of pores index of each group grating is-6.3; According to the face dam that above-mentioned parameter is made, one-shot forming, does not need repeatedly to debug, decrease experiment number, when not affecting dam body frost heave under infiltrative condition, distortion is less, dam body internal penetration good stability, low compressibility, high shear strength, face dam long service life.
Embodiment 2:
As shown in Fig. 1 ~ 7, cold district is based on the bedding material gradation design optimization method of distribution of pores index, and preferably, the density design that rolls of bedding material is 0.80; The fine sand grain diameter replaced in the fine sand group of powder clay is 0.06mm, and the content of fine sand group is 8.75%, and other gratings are with thanking to rad grating; In bedding material, the distribution of pores index of each group grating is-6.2; According to the face dam that above-mentioned parameter is made, one-shot forming, does not need repeatedly to debug, decrease experiment number, when not affecting dam body frost heave under infiltrative condition, distortion is less, dam body internal penetration good stability, low compressibility, high shear strength, face dam long service life.
Embodiment 3:
As shown in Fig. 1 ~ 7, cold district is based on the bedding material gradation design optimization method of distribution of pores index, and preferably, the density design that rolls of bedding material is 0.78; The fine sand grain diameter replaced in the fine sand group of powder clay is 0.07mm, and the content of fine sand group is 4%, and other gratings are with thanking to rad grating; In bedding material, the distribution of pores index of each group grating is-6.25; According to the face dam that above-mentioned parameter is made, one-shot forming, does not need repeatedly to debug, decrease experiment number, when not affecting dam body frost heave under infiltrative condition, distortion is less, dam body internal penetration good stability, low compressibility, high shear strength, face dam long service life.
Embodiment 4:
As shown in Fig. 1 ~ 7, cold district is based on the bedding material gradation design optimization method of distribution of pores index, and preferably, the density design that rolls of bedding material is 0.79; The fine sand grain diameter replaced in the fine sand group of powder clay is 0.065mm, and the content of fine sand group is 8%, and other gratings are with thanking to rad grating; In bedding material, the distribution of pores index of each group grating is-6.28; According to the face dam that above-mentioned parameter is made, one-shot forming, does not need repeatedly to debug, decrease experiment number, when not affecting dam body frost heave under infiltrative condition, distortion is less, dam body internal penetration good stability, low compressibility, high shear strength, face dam long service life.
The above is only the preferred embodiment of the present invention; be noted that for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (9)

1. cold district is based on the bedding material gradation design optimization method of distribution of pores index, it is characterized in that: comprise the following steps:
S01, rolls the determination of density: the density design that rolls of bedding material is 0.75 ~ 0.80, to make the existing higher relative density of bedding material, does not produce larger frost-heaving deformation again;
S02, fine sand group replaces powder clay: the fine sand grain diameter replaced in the fine sand group of powder clay is 0.075 ~ 0.6 mm, and other gratings are with thanking to rad grating;
S03, the determination of distribution of pores index: in bedding material, the distribution of pores index of each group grating is-6.3 ~-6.2;
S04, gradation adjustment: carry out frost heave and infiltration test, whether test sample frozen-heave factor, transmission coefficient meet engine request; If sample transmission coefficient is excessive, then distribution of pores index should tune up in above-mentioned number range; If transmission coefficient is too small or frozen-heave factor is excessive, then distribution of pores index should be turned down in above-mentioned number range; Adjustment is until reasonably grating appearance.
2. cold district according to claim 1 is based on the bedding material gradation design optimization method of distribution of pores index, it is characterized in that: described grating comprises described fine sand group and particle diameter is 80 ~ 100mm coarse gravel group; Described grating is continuous grading; Suppose that the particle size in each grating is consistent, be the arithmetic mean of instantaneous value of maximum particle diameter and minimum grain size; Suppose that the particle in each grating is spherical and is uniformly distributed.
3. cold district according to claim 1 is based on the bedding material gradation design optimization method of distribution of pores index, it is characterized in that: described in roll density and be preferably 0.78 ~ 0.80.
4. cold district according to claim 1 is based on the bedding material gradation design optimization method of distribution of pores index, it is characterized in that: the fine sand grain diameter in described fine sand group is 0.07 ~ 0.6 mm.
5. the cold district according to claim 1 or 4, based on the bedding material gradation design optimization method of distribution of pores index, is characterized in that: the fine sand grain diameter in described fine sand group is 0.065 ~ 0.6 mm.
6. cold district according to claim 1 is based on the bedding material gradation design optimization method of distribution of pores index, it is characterized in that: described distribution of pores index is-6.25 ~-6.2.
7. cold district according to claim 1 is based on the bedding material gradation design optimization method of distribution of pores index, it is characterized in that: described distribution of pores index is-6.3 ~-6.25.
8. cold district according to claim 1 is based on the bedding material gradation design optimization method of distribution of pores index, it is characterized in that: the content range of described fine sand group shared by all gratings is 3.75 ~ 8.75%.
9. cold district according to claim 8 is based on the bedding material gradation design optimization method of distribution of pores index, it is characterized in that: the content range of described fine sand group shared by all gratings is 4 ~ 8%.
CN201510254186.8A 2015-05-18 2015-05-18 Cold district bedding material based on distribution of pores index gradation design optimization method Expired - Fee Related CN104895017B (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106498898A (en) * 2016-11-22 2017-03-15 河海大学 A kind of earth and stone material Gradation Optimization method based on fractal theory and physical mechanics test
CN110191988A (en) * 2016-11-18 2019-08-30 中国电建集团贵阳勘测设计研究院有限公司 A kind of cushion of dam with face slab material safety appraisement of structure method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110191988A (en) * 2016-11-18 2019-08-30 中国电建集团贵阳勘测设计研究院有限公司 A kind of cushion of dam with face slab material safety appraisement of structure method
CN106498898A (en) * 2016-11-22 2017-03-15 河海大学 A kind of earth and stone material Gradation Optimization method based on fractal theory and physical mechanics test
CN106498898B (en) * 2016-11-22 2019-03-05 河海大学 A kind of earth and stone material Gradation Optimization method based on fractal theory and physical mechanics test

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