CN101049718A - Method for determining optimized mixture ratio of mixing lightweight soil - Google Patents

Abstract

A method for determining the optimized formula of a high-weight mixed clay includes such steps as determining the strength according to its surficial load, determining the density according to load bearing power of lower layer, thickness and the diffusion stress of said surficial load, and orthogonal test.

Description

A kind of method for determining optimized mixture ratio of mixing lightweight soil

(1) technical field

The present invention relates to definite method of mixed light weight soil optimum mix proportion, be applicable to that road is widened, road bankets, adopt mixed light weight soil determining in the engineerings such as the abutment back of the body bankets, underground engineering and pipeline as the optimization match ratio of backfill.Belong to the civil engineering technical field.

(2) background technology

Mixed light weight soil is made of by a certain percentage raw material soil, curing agent, water, light material etc., and its intensity and density all can be regulated.Intensity and density for the mixed light weight soil of different its demands of engineering are also different, and too high meeting makes the curing agent addition too much as desired strength, easily causes density excessive, less economical, can not satisfy the requirement of lightweight.If require density too small, can make the addition of light material too much, easily cause intensity low excessively, can not satisfy the requirement of engineering safety equally.The intensity and the density determining method of the mixed light-weight soils that adopts are rule of thumb definite at present, do not have unified foundation, and the result is also very unreliable and cost is high.Therefore, how to determine the needed intensity and the density of light-weight soils rapidly and accurately at different engineerings, optimize match ratio thereby obtain mixed light weight soil, the cooperation specific energy engineering demands that makes light-weight soils is a current engineering circle problem anxious to be solved.

(3) summary of the invention

The objective of the invention is to solve existing method implementation cost height, random strong, the unreliable shortcoming that maybe can not embody particularity of result, provide principle clear and definite, workable, with low cost, result of use is good, be convenient to the definite method at the mixed light weight soil optimal proportion in the different engineerings.

For reaching goal of the invention the technical solution used in the present invention be:

A kind of mixed light weight soil is optimized definite method of match ratio, and described method is at first to obtain the intensity that the mixed light weight soil needs reach according to mixed light weight soil surface layer load; The stress that can load acts on the diffusion of light-weight soils surface load by the bearing capacity of light-weight soils subjacent bed, light-weight soils thickness, subgrade and pavement, friendship is tried to achieve the density that mixed light weight soil need satisfy again; By intensity and the density that light-weight soils need satisfy, carry out orthogonal test and promptly get mixed light weight soil optimization match ratio.

Further, described mixed light weight soil is optimized definite method of match ratio, comprises following sequential steps:

(1) at first determines to act on mixed light weight soil surface all loads (formula 1 in the following intensity) according to the engineering design situation, carrying out stress diffusion (formula 2 in the following intensity) by described all loads analyzes, try to achieve and be applied to mixed light weight soil surface layer load, according to the mixed light weight soil surface layer load that obtains, obtain the intensity that mixed light weight soil need reach according to the limit states design method of expressing with partial safety factor;

(2) determine the bearing capacity that the light-weight soils subjacent bed can reach by the engineering geological property of light-weight soils subjacent bed, according to bearing capacity, light-weight soils thickness, roadbed and the surface layer of described subjacent bed, action of traffic loading in the diffusion-induced stress of light-weight soils surface load-, try to achieve the density that mixed light weight soil need satisfy according to the limit states design method that partial safety factor is expressed, obtain needed density according to the step 4-8 formula of back;

(3) intensity and the density that need be satisfied by (1) step and (2) light-weight soils that obtains of step is analyzed the match ratio that just can obtain optimum according to the result of orthogonal test.

The strength determining method of concrete mixed light weight soil as backfill, described method is as follows:

(1) according to formula 1: ${\mathrm{\σ}}_1=\underset{i=i}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\γ}}_i\·h_i$ Calculating dead load acts on mixed light weight soil and builds vertical diffusion-induced stress on the body;

In the formula 1:

σ ₁For roadbed and road surface act on the diffusion-induced stress of light-weight soils surface layer, the kN/m of unit ²

γ _iBe the severe of roadbed and road surface layers of material, the kN/m of unit ³(the severe value of material referring to: highway subgrade design specification JTG D30-2004, highway cement concrete pavement design specification JTG D40-2002, " worker road engineering standard " JTG B01-2003)

h _iBe the bed thickness of roadbed and road surface layers of material, the m of unit;

(2) according to formula 2: σ ₂=[P (1+ ξ)]/[(B+2ztan θ) (L+2ztan θ)] calculates and acts on the vertical diffusion-induced stress that mixed light weight soil is built the traffic loading above the body;

In the formula 2:

σ ₂Be the diffusion-induced stress of action of traffic loading in the light-weight soils surface layer, the kN/m of unit ²

P is a wheel load, the kN of unit;

ξ is impact coefficient (ξ=0.1 ~ 0.5);

B is a rear wheel wheel bandwidth, the m of unit;

L is a rear wheel length contiguously, the m of unit;

Above Several Factors is definite according to " worker road engineering standard " JTG B01-2003,

Get standard value;

θ is the stress angle of flare (span sees Table 1) of load;

Z is the bed thickness sum of roadbed and each layer of road surface, the m of unit;

(3) according to formula 3:Q _u=σ ₁λ ₁+ σ ₂λ ₂, the limiting condition of expressing according to partial safety factor calculates the intensity that mixed light weight soil need reach;

In the formula 3:

σ ₁For roadbed and road surface act on the diffusion-induced stress of light-weight soils surface layer, the kN/m of unit ²

σ ₂Be the diffusion-induced stress of action of traffic loading in the light-weight soils surface layer, the kN/m of unit ²

λ ₁Act on the subitem resistance coefficient (span sees Table 2) of light-weight soils surface layer for roadbed and road surface;

λ ₂Be the subitem resistance coefficient (span see Table 2) of action of traffic loading in the light-weight soils surface layer;

Q _uBe the intensity level that described mixed light weight soil will reach, the kN/m of unit ²

Table 1: the value of the stress angle of flare θ of load

Annotate: for the concrete road surface, stress angle of flare θ=45 °.

Table 2: the value of subitem resistance coefficient

Road quality classification	λ 1	λ 2
			Highway	3	2
Class I highway	2.5	1.7
			Class II highway	2.0	1.5
Class III highway	1.5	1.3
			Class IV highway	1.3	1.1
The outer highway of grade	1	1

The density determining method as the mixed light weight soil of backfill of recommending, described method is as follows:

(1) according to formula 1: ${\mathrm{\σ}}_1=\underset{i=i}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\γ}}_i\·h_i$ Calculating dead load acts on mixed light weight soil and builds vertical diffusion-induced stress on the body;

In the formula 1,

σ ₁For roadbed and road surface act on the diffusion-induced stress of light-weight soils surface layer, the kN/m of unit ²

γ _iBe the severe of roadbed and road surface layers of material, the kN/m of unit ³(the severe value of material referring to: highway subgrade design specification JTG D30-2004, highway cement concrete pavement design specification JTG D40-2002, " worker road engineering standard " JTG B01-2003)

h _iBe the bed thickness of roadbed and road surface layers of material, the m of unit;

(2) according to formula 4: σ ₂=γ _{Light-weight soils}H _{Light-weight soils}Calculating light-weight soils fill material acts on the vertical diffusion-induced stress on the subjacent bed;

In the formula 4,

σ ₂For light-weight soils acts on diffusion-induced stress on the subjacent bed, the kN/m of unit ²

γ _{Light-weight soils}Be the severe of light-weight soils fill material, the kN/m of unit ³

h _{Light-weight soils}Be the bed thickness of light-weight soils fill material, the m of unit;

(3) according to formula 5: σ ₃=[P (1+ ξ)]/[(B+2ztan θ) (L+2ztan θ)] calculates and acts on the vertical diffusion-induced stress that mixed light weight soil is built the traffic loading above the body;

In the formula 5,

σ ₃Be the diffusion-induced stress of action of traffic loading in the light-weight soils surface layer, the kN/m of unit ²

P is a wheel load, the kN of unit;

ξ is impact coefficient (ξ=0.1 ~ 0.5);

B is a rear wheel wheel bandwidth, the m of unit;

L is a rear wheel length contiguously, the m of unit; (wheel load, impact coefficient, rear wheel wheel bandwidth and rear wheel be length contiguously, can be according to " worker road engineering standard "

JTG B01-2003 determines, gets standard value)

θ is the stress angle of flare (seeing Table 1) of load;

Z is the bed thickness sum of roadbed and each layer of road surface, the m of unit;

Table 1: the value of the stress angle of flare θ of load

Fixed)	0.25	0.5
			3	6°	23°
5	10°	25°
			10	20°	30°

Annotate: for the concrete road surface, stress angle of flare θ=45 °.

(4) by engineering geological property and this soil layer place degree of depth of light-weight soils subjacent bed, according to formula 6:f=f _a+ η _bγ (b-3)+η _dγ ₀(d-0.5) calculate the bearing capacity that the light-weight soils subjacent bed can reach;

In the formula 6,

F is a light-weight soils subjacent bed foundation bearing capacity design load, the kN/m of unit ²

f _aBe light-weight soils subjacent bed characteristic value of foundation bearing capacity, can look into " Code for design of building " and choose, the kN/m of unit ²

γ is the natural unit weight of light-weight soils subjacent bed, the following buoyant unit weight, the kN/m of unit used of level of ground water ²

B is the light-weight soils width that bankets, the m of unit; When width during less than 3m by 3m, during greater than 6m by 6m;

D is the road surface to the banket degree of depth of bottom surface of light-weight soils, the m of unit;

η _b, η _dBe bearing capacity correction factor, can look into " Code for design of building " and choose corresponding to foundation width and buried depth;

(5) according to formula 7:

The limiting condition of expressing according to partial safety factor calculates the density value that mixed light weight soil need satisfy;

In the formula 7,

σ ₁For roadbed and road surface act on the diffusion-induced stress of light-weight soils surface layer, the kN/m of unit ²

σ ₃Be the diffusion-induced stress of action of traffic loading in the light-weight soils surface layer, the kN/m of unit ²

λ ₁Be the subitem resistance coefficient (see Table 2) of load actions such as roadbed and road surface in the subjacent bed surface layer;

λ ₂For light-weight soils is banketed load action in the subitem resistance coefficient (seeing Table 2) of subjacent bed surface layer;

λ ₃Be the subitem resistance coefficient (see Table 2) of action of traffic loading in the subjacent bed surface layer;

The ρ light-weight soils is the density value that mixed light weight soil will reach.

Table 2: the value of subitem resistance coefficient

Road quality classification	λ 1Or λ 2	λ 3
			Highway	3	2
Class I highway	2.5	1.7
			Class II highway	2.0	1.5
Class III highway	1.5	1.3
			Class IV highway	1.3	1.1
The outer highway of grade	1	1

Beneficial effect of the present invention is mainly reflected in: the intensity that mixed light weight soil need should reach and definite method principle of density requirements are clear and definite, thereby the match ratio of the optimum that obtains according to orthogonal test is workable, with low cost, result of use is good, has bigger implementary value and economic results in society.

(4) description of drawings

Fig. 1 is a light-weight soils surface load situation map

Fig. 2 is the load situation figure of light-weight soils subjacent bed

The gravitation figure that Fig. 3 causes for the road surface live load

(5) specific embodiment

The present invention is described further below in conjunction with specific embodiment, but protection scope of the present invention is not limited in this:

Embodiment 1:

High-grade highway adopts mixed light weight soil as backfill in order to alleviate the deadweight of banketing, and the depth of fill is 5m.According to road surface and subgrade Design situation as can be known, the thick 35cm of cement concrete pavement, two-ash broken stones layer 70cm, reinforced concrete protective layer is thick to be 20cm, then the bed thickness on roadbed and road surface is z=1.25m.

The light-weight soils surface is by concrete road surface (thick 35cm, r ₁=24kN/m ³), basic unit (cement stabilized macadam bed thickness 70cm, r ₁=23kN/m ³) and armoured concrete slab protective layer (thickness of slab 20cm, r ₁=25kN/m ³) weight stress that produces is (according to step (1)):

${\mathrm{\σ}}_1=\underset{i=i}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\γ}}_i\·h_i=24\×0.35+23\×0.70+25\×0.2=29.5\mathrm{kN}/m^2$

Can obtain the diffusion-induced stress of action of traffic loading according to step (2) in the light-weight soils surface layer:

$=56.60\mathrm{kN}/m^2$

Get corresponding partial safety factor λ according to step (3) ₁=3; λ ₂=2, the demand intensity that can obtain mixed light weight soil is:

Q _u＝σ ₁·λ ₁+σ ₂·λ ₂＝29.5×3+56.60×2＝171.7kN/m ²

The light-weight soils subjacent bed is a clay, and severe is 17kN/m ³, the characteristic value of bearing capacity is 152kN/m ²

The light-weight soils surface is by concrete road surface (thick 35cm, r ₁=24kN/m ³), basic unit (cement stabilized macadam bed thickness 70cm, r ₁=23kN/m ³) and armoured concrete slab protective layer (thickness of slab 20cm, r ₁=25kN/m ³) weight stress that produces is:

${\mathrm{\σ}}_1=\underset{i=i}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\γ}}_i\·h_i=24\×0.35+23\×0.70+25\×0.2=29.5\mathrm{kN}/m^2$

Action of traffic loading in the diffusion-induced stress of light-weight soils surface layer is:

$=1.99\mathrm{kN}/m^2$

Engineering geological condition according to subjacent bed is got r ₀=17kN/m ³, η _b=0; η _d=1.1 obtain bearing capacity is:

F=f _a+ η _bγ (b-3)+η _dγ ₀(d-0.5)=152+0.3 * 17 * 3+1.3 * 17 * 5.5=273.55kN/m ²Get corresponding partial safety factor λ ₁=3; λ ₂=2, the demand density that can obtain mixed light weight soil is:

The light-weight soils density that satisfies requirement of engineering as can be known is 1.05g/cm ³

Orthogonal test factor and be horizontally disposed with table (is that 1500g is a benchmark with sand)

Level	Factor
				Cement (g)	EPS(g)	Water (g)
	1 2 3	80(5.33％) 120(8.0％) 160(10.67％)	20(1.33％) 30(2.00％) 40(2.67％)				250(16.7％) 300(20.0％) 350(23.3％)

Carry out the test of intensity and density according to orthogonal test table, obtain corresponding result of the test respectively, as shown in the table:

Tested number	A	Empty row	B	C	Unconfined compressive strength normalization	The normalization of no lateral confinement resistance to compression density	Overall target
								1	1	1	1	1	158	1.22	1.83
2	1	2	2	2	130	1.08	0.71
								3	1	3	3	3	101	0.96	1.6
4	2	1	2	3	216	1.09	0.85
								5	2	2	3	1	180	0.97	0.89
6	2	3	1	2	255	1.24	2.74
								7	3	1	3	2	252	0.98	1.51
8	3	2	1	3	324	1.1	2.03
								9	3	3	2	1	432	1.35	5.61
Ti1	4.19		6.6	7.61
								Ti2	3.63		7.17	6.74
Ti3	9.95		7.6	9
								Ki1	1.40		2.20	2.54
Ki2	1.21		2.39	2.25
								Ki3	3.32		2.53	3.00
Optimize the result	Getting A2 is that cement content is 120		Getting B1 is that EPS content is 20	Getting C2 is that water content is 300									So optimum mix proportion is a sand: cement: EPS: water=1500: 120: 20: 300 (mass ratioes)

Annotate: overall target:

Carried out the test of intensity and density test by above-mentioned optimum mix proportion, the result shows that the light-weight soils intensity of actual measurement is 186kPa, and the intensity calculated value of determining by match ratio and the error of test value are 7.6%, can satisfy the requirement of strength of engineering demand.The density of actual measurement light-weight soils is 1.07kg/m ³, the density measured value of determining by match ratio and the error of test value are 1.8%, can satisfy the density requirements of engineering demand.

Claims (2)

1. a method for determining optimized mixture ratio of mixing lightweight soil is characterized in that described method is at first to obtain the intensity that the mixed light weight soil needs reach according to mixed light weight soil surface layer load; The stress that can load acts on the diffusion of light-weight soils surface load by the bearing capacity of light-weight soils subjacent bed, light-weight soils thickness, subgrade and pavement, friendship is tried to achieve the density that mixed light weight soil need satisfy again; By intensity and the density that light-weight soils need satisfy, carry out orthogonal test and promptly get mixed light weight soil optimization match ratio.

2. method for determining optimized mixture ratio of mixing lightweight soil as claimed in claim 1 comprises following sequential steps:

(A) at first determine to act on all load formula 1 of mixed light weight soil surface according to the engineering design situation, carrying out stress diffusion formula 2 by described all loads analyzes, try to achieve and to be applied to mixed light weight soil surface layer load, according to the mixed light weight soil surface layer load that obtains, according to obtaining the strength formula 3 that mixed light weight soil need reach based on the limit states design method of probability theory or the limit states design method of expressing according to partial safety factor;

(1) according to formula 1: ${\mathrm{\σ}}_1=\underset{i=i}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\γ}}_i\·h_i$ Calculating dead load acts on mixed light weight soil and builds vertical diffusion-induced stress on the body;

In the formula 1:

σ ₁For roadbed and road surface act on the diffusion-induced stress of light-weight soils surface layer, the kN/m of unit ²

γ _iBe the severe of roadbed and road surface layers of material, the kN/m of unit ³(the severe value of material referring to: highway subgrade design specification JTG D30-2004, highway cement concrete pavement design specification JTG D40-2002, " worker road engineering standard " JTG B01-2003)

h _iBe the bed thickness of roadbed and road surface layers of material, the m of unit;

(2) according to formula 2: σ ₂=[P (1+ ξ)]/[(B+2ztan θ) (L+2ztan θ)] calculates and acts on the vertical diffusion-induced stress that mixed light weight soil is built the traffic loading above the body;

In the formula 2:

σ ₂Be the diffusion-induced stress of action of traffic loading in the light-weight soils surface layer, the kN/m of unit ²

P is a wheel load, the kN of unit;

ξ is impact coefficient (ξ=0.1 ~ 0.5);

B is a rear wheel wheel bandwidth, the m of unit;

L is a rear wheel length contiguously, the m of unit;

Above Several Factors is determined according to " worker road engineering standard " JTG B01-2003, is got standard value;

θ is the stress angle of flare (span sees Table 1) of load;

Z is the bed thickness sum of roadbed and each layer of road surface, the m of unit;

(3) according to formula 3:Q _u=σ ₁λ ₁+ σ ₂λ ₂, the limiting condition of expressing according to partial safety factor calculates the intensity that mixed light weight soil need reach;

In the formula 3:

σ ₁For roadbed and road surface act on the diffusion-induced stress of light-weight soils surface layer, the kN/m of unit ²

σ ₂Be the diffusion-induced stress of action of traffic loading in the light-weight soils surface layer, the kN/m of unit ²

λ ₁Act on the subitem resistance coefficient of light-weight soils surface layer for roadbed and road surface

(B) determine the bearing capacity that the light-weight soils subjacent bed can reach by the engineering geological property of light-weight soils subjacent bed, according to bearing capacity, light-weight soils thickness, roadbed and the surface layer of described subjacent bed, action of traffic loading in the diffusion-induced stress of light-weight soils surface load-, try to achieve the density that mixed light weight soil need satisfy according to the limit states design method that partial safety factor is expressed, obtain needed density according to formula 1, formula 4～7;

(1) according to formula 1: ${\mathrm{\σ}}_1=\underset{i=i}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\γ}}_i{\·h}_i$ Calculating dead load acts on mixed light weight soil and builds vertical diffusion-induced stress on the body;

In the formula 1,

σ ₁For roadbed and road surface act on the diffusion-induced stress of light-weight soils surface layer, the kN/m of unit ²

γ _iBe the severe of roadbed and road surface layers of material, the kN/m of unit ³(the severe value of material referring to: highway subgrade design specification JTG D30-2004, highway cement concrete pavement design specification JTG D40-2002, " worker road engineering standard " JTG B01-2003)

h _iBe the bed thickness of roadbed and road surface layers of material, the m of unit;

(2) according to formula 4: σ ₂=γ _{Light-weight soils}H _{Light-weight soils}Calculating light-weight soils fill material acts on the vertical diffusion-induced stress on the subjacent bed;

In the formula 4,

σ ₂For light-weight soils acts on diffusion-induced stress on the subjacent bed, the kN/m of unit ²

γ _{Light-weight soils}Be the severe of light-weight soils fill material, the kN/m of unit ³

h _{Light-weight soils}Be the bed thickness of light-weight soils fill material, the m of unit;

(3) according to formula 5: σ ₃=[P (1+ ξ)]/[(B+2ztan θ) (L+2ztan θ)] calculates and acts on the vertical diffusion-induced stress that mixed light weight soil is built the traffic loading above the body;

In the formula 5,

σ ₃Be the diffusion-induced stress of action of traffic loading in the light-weight soils surface layer, the kN/m of unit ²

P is a wheel load, the kN of unit;

ξ is impact coefficient (ξ=0.1 ~ 0.5);

B is a rear wheel wheel bandwidth, the m of unit;

L is a rear wheel length contiguously, the m of unit; (wheel load, impact coefficient, rear wheel wheel bandwidth and rear wheel be length contiguously, can determine according to " worker road engineering standard " JTGB01-2003, gets standard value)

θ is the stress angle of flare (seeing Table 1) of load;

Z is the bed thickness sum of roadbed and each layer of road surface, the m of unit;

(4) by engineering geological property and this soil layer place degree of depth of light-weight soils subjacent bed, according to formula 6:f=f _a+ η _bγ (b-3)+η _dγ ₀(d-0.5) calculate the bearing capacity that the light-weight soils subjacent bed can reach;

In the formula 6,

F is a light-weight soils subjacent bed foundation bearing capacity design load, the kN/m of unit ²

f _aBe light-weight soils subjacent bed characteristic value of foundation bearing capacity, can look into " Code for design of building " and choose, the kN/m of unit ²

γ is the natural unit weight of light-weight soils subjacent bed, the following buoyant unit weight, the kN/m of unit used of level of ground water ²

B is the light-weight soils width that bankets, the m of unit; When width during less than 3m by 3m, during greater than 6m by 6m;

D is the road surface to the banket degree of depth of bottom surface of light-weight soils, the m of unit;

η _b, η _dBe bearing capacity correction factor, can look into " Code for design of building " and choose corresponding to foundation width and buried depth;

(5) according to formula 7:

The limiting condition of expressing according to partial safety factor calculates the density value that mixed light weight soil need satisfy;

In the formula 7,

σ ₁For roadbed and road surface act on the diffusion-induced stress of light-weight soils surface layer, the kN/m of unit ²

σ ₃Be the diffusion-induced stress of action of traffic loading in the light-weight soils surface layer, the kN/m of unit ²

λ ₁Be the subitem resistance coefficient (see Table 2) of load actions such as roadbed and road surface in the subjacent bed surface layer;

λ ₂For light-weight soils is banketed load action in the subitem resistance coefficient (seeing Table 2) of subjacent bed surface layer;

λ ₃Be the subitem resistance coefficient (see Table 2) of action of traffic loading in the subjacent bed surface layer;

ρ _{Light-weight soils}The density value that will reach for mixed light weight soil.

(C) intensity and the density that need be satisfied by (1) step and (2) light-weight soils that obtains of step is analyzed the match ratio that just can obtain optimum according to the result of orthogonal test.

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