CN100580451C - Probe for in-situ real time measurement of saturated fine soil borizontal stress and measuring, calculating method - Google Patents

Abstract

The present invention provides a probe for in situ real time measurement saturated fine soil horizontal stress and a measurement and a calculating methods. The probe is characterized in that one end of the probe is a thread head, and the other end is conical, wherein the middle part of the probe is cylindrical, and is provided with a pressure protecting groove. Conducting liquid is filled in a central blind hole of the probe, and a pressure sensor is arranged in the conducting liquid in the central blind hole in a sealing mode. A concave part is arranged on the outer wall of a cylinder of the probe, and the concave part is sealed by an isolation conducting sheet which has the same dimension of the outer edge of the cylinder of the probe. The conducting liquid communicated with the central blind hole of the probe is arranged in the concave part sealed by the isolation conducting sheet. The present invention has the following measurement and computation methods that: a relational curve of horizontal stress R of a saturation soil layer depth position and time t is obtained through measurement; the horizontal stress of horizontal stress R0 of initial time and completion of dissipation of excess pore pressure is calculated by a three point calculation method; the consolidation degree Ut is calculated, and a horizontal consolidation coefficient Ch and a quiescence coefficient of lateral pressure K0 are calculated. A method for measuring horizontal stress of fine granulated saturation soil at original place in real time calculates out degree U of consolidation and horizontal consolidation coefficient C as well as static side pressure coefficient K by obtaining relation curve of horizontal pressure R at saturation soil layer deep position to time T and by applying three - points calculation means to calculate horizontal stress R1 at initial time and horizontal stress at time of finalizing excess pore water pressure evanish . The probe for realizing said method is also disclosed.

Description

The probe of in-situ real time measuring saturated fine soil borizontal stress and measurement, computing method

Technical field

The present invention relates to geotechnical engineering investigation and measure the instrument of saturated fine grained soil horizontal stress and measurement thereof, computing method, particularly be a kind of probe of in-situ real time measuring saturated fine soil borizontal stress and measurement, computing method.

Background technology

At present, the isoparametric mensuration of Stationary side pressure coefficient, the coefficient of consolidation on stratum is generally all finished by boring with sampling, shop experiment.Finishing measurement will be through a series of processes such as boring with sampling, transportation, specimen preparation and tests, and measuring process inevitably can cause the disturbance of soil sample, and this must influence accuracy of experimental results.This method length consuming time simultaneously, the expense height.

In Japan, usually make probe and come these parameters of in-site detecting, the high 215mm of this Stress shovel, wide 98mm, thick 5mm by Stress shovel.But, only be applicable to the weak soil of static point resistance less than 0.6MPa because the rigidity of this Stress shovel shovel head is less; The unit that also has the thickness of Stress shovel is increased to 8mm, but also only suitable static point resistance is less than the weak soil of 0.8MPa on the basis of existing Stress shovel.

In addition, the hole that is to use that also has presses probe to come the test beds coefficient of consolidation, and the hole presses probe to be conical structure.It is the coefficient of consolidation of estimating the stratum by the dissipation of measuring mesoporosity, stratum water pressure.But the hole presses probe to have the shortcoming of complicated operation, promptly needs before the test to keep probe at vacuum state, simultaneously its direct lateral pressure coefficient of test beds.

Aspect calculation of parameter determined, the Stress shovel test was the stationary value of the horizontal stress measured according to Stress shovel and the Stationary side pressure coefficient that experience factor calculates soil layer, but the stationary value of measuring not necessarily is exactly an end value.The hole presses probe to determine that with Stress shovel the method for horizontal consolidation coefficient is similar, a kind of is to determine by curve fitting method, another kind is that pore water pressure force parameter computation of table lookup is determined when destroying according to the rigidity index of the soil body and the soil body, the calculation procedure complexity, and the human factor influence is big.

Summary of the invention

The objective of the invention is to overcome the deficiency of above-mentioned technology, provide a kind of in atmospheric environment for weak soil, saturated general cohesive soil or the accurate testing level stress of powder fine sand original position, provide a kind of intensity height, the measurements and calculations probe of in-situ real time measuring saturated fine soil borizontal stress and measurement easily, computing method for directly calculating the coefficient of consolidation, Stationary side pressure coefficient.

Solving the problems of the technologies described above the technical scheme that is adopted is:

A kind of probe of in-situ real time measuring saturated fine soil borizontal stress, an end of this probe are the thread heads that is connected with external spiral depression bar, and the other end of this probe is conical, and the middle part of probe is have the pressure protect groove cylindrical; Be full of conductive liquid in the central blind hole of probe, the pressure transducer sealing is arranged in the interior conductive liquid of central blind hole; Probe middle part right cylinder outer wall is provided with recess, and the insulate conduction thin slice consistent with the cylinder physical dimension of probe seals this recess, in the recess that is sealed by the insulate conduction thin slice conductive liquid that is communicated with the center probe blind hole is arranged.

A kind of measuring method and computing method of using the probe of in-situ real time measuring saturated fine soil borizontal stress, described measuring method and computing method are to derive the horizontal consolidation coefficient (C of probe (8) test place saturated fine grained soil layer by calculating according to the saturated fine grained soil horizontal stress of measuring _h) and static coefficient of horizontal pressure (K ₀), its measurement and calculation procedure are as follows:

(1), measurement and the calculated level coefficient of consolidation (C _h) step as follows:

1.. obtain the horizontal stress (R) at saturated fine grained soil layer MTD place and the curve of time (t) relation by measurement: be connected pressure receiving converter (7) with probe (8) and record the horizontal stress (R) at saturated fine grained soil layer MTD place and the curve of time (t) relation;

2. calculate initial time horizontal stress (R with 3 computing methods ₀) and the excess pore water pressure horizontal stress (R when finishing that dissipates _f), concrete calculation procedure is as follows:

A, on step horizontal stress (R) 1. and time (t) the relation curve section of beginning, choose two moment (t ₁, t ₂), the stress value of finding out their correspondences is respectively (R ₁, R ₂); Choose (t constantly at horizontal stress (R) and time (t) relation curve back segment ₃), find out the stress value (R of its correspondence ₃);

B, calculate initial time horizontal stress (R respectively with following formula (7) and (8) ₀) and the excess pore water pressure horizontal stress (R when finishing that dissipates _f) value:

$R_0=(R_1-R_2\sqrt{\frac{t_1}{t_2}})/(1-\sqrt{\frac{t_1}{t_2}})---\left(7\right)$

$R_f=R_0-\frac{R_0-R_3}{{(1-{((R_0-R_3)(\sqrt{t_2}-\sqrt{t_1})/(R_1-R_2)\sqrt{t_3})}^{5.6})}^{0.179}}---\left(8\right)$

3.. calculate the degree of consolidation (U _t): utilize formula (6) to calculate the pop one's head in the constantly degree of consolidation (U at (8) MTD place of t _t), formula (6) is as follows:

$U_t=\frac{u_0-u_t}{u_0}=\frac{R_0-{\mathrm{\σ}}^{\′}-u-(R_t-{\mathrm{\σ}}^{\′}-u)}{R_0-{\mathrm{\σ}}^{\′}-u}=\frac{R_0-R_t}{R_0-R_f}---\left(6\right)$

4.. the calculated level coefficient of consolidation (C _h):

A, according to the pop one's head in the constantly degree of consolidation (U at (8) MTD place of t _t) value, by following formula (2) or (4), obtain t ₁, t ₂, t ₃The time time factor T _V1, T _V2, T _V3Numerical value:

$T_v=\frac{\frac{\mathrm{\π}}{4}{U}^2}{{(1-U^{5.6})}^{0.357}}---\left(4\right)$

B, calculate horizontal consolidation coefficient (C according to following formula (5) _h):

$C_h=\frac{T_{v1}{r}^2}{t_1}=\frac{T_{v2}{r}^2}{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}=\frac{T_{v3}{r}^2}{t_3}---\left(5\right)$

(in the formula: r---expression probe (8) conehead bottom surface radius)

(2), calculate static coefficient of horizontal pressure (K ₀) step is as follows:

Calculate Stationary side pressure coefficient (K according to following formula ₀)

$K_0=\frac{R_f-u}{{\mathrm{\&sigma;}}_v-u}---\left(9\right)$

In the formula: the hydrostatic force at u-test point place; U=r _wh

σ _v-test point place soil vertically to total stress; σ _v=∑ r _ih _i

r _wThe severe of-water;

The above height of water level of h-test point;

r _iThe severe of the above i layer soil of-test point;

h _iThe thickness of the above i layer soil of-test point.

The invention has the beneficial effects as follows: this probe adopts cylindrical structural, the total compact, use laser-beam welding machine the insulate conduction thin slice is welded on the right cylinder of probe, make that it reaches that firm welding, thermal deformation are little, elasticity and the little purpose of conducted signal distortion.External overall forms hermetically-sealed construction, and dependability is higher.Material adopts thermally-stabilised, superhard sedimentation type alloy steel.More can be applicable to the geology detecting under the rugged surroundings.Not only go for weak soil, saturated general cohesive soil, powder fine sand and hard stratum.

The present invention records horizontal stress and time relation curve according to the soil mechanics consolidation theory according to probe, adopts three point method to calculate probe and is pressed into the initial time horizontal stress R of test point place ₀Horizontal stress R when dissipation is finished with excess pore water pressure _fAnd then the degree of consolidation U at calculating t moment MTD place _tWith time factor T _VtLast calculated level coefficient of consolidation C _hWith static side pressure COEFFICIENT K ₀This method calculation procedure is simple, quick, clear concept.

Computing method of the present invention are saved time than existing measurement computing method and are invested.The present invention has overcome the little shortcoming of prior art Stress shovel rigidity, has also overcome the hole and has pressed probe just to measure the shortcoming of pore water pressure and complicated operation.

Description of drawings

Fig. 1 is a partial cutaway structural representation of the present invention;

Fig. 2 is that probe records horizontal stress and time relation curve.

Embodiment

Below in conjunction with accompanying drawing embodiments of the invention are described in further detail:

Fig. 1 is a partial cutaway structural representation of the present invention; Fig. 2 is that probe records horizontal stress and time relation curve.

As shown in the figure, the invention provides a kind of probe 8 of in-situ real time measuring saturated fine soil borizontal stress, one end of this probe 8 is the thread heads that are connected with external spiral depression bar, and probe 8 the other end be conical, and the purpose of employing conical structure is to be convenient to pop one's head in 8 be pressed into soil layer.

Probe 8 middle part is cylindrical, is provided with the groove of certain width in cylindrical outer, promptly is referred to as pressure protect groove 6, can be subjected to certain resistance when probe 8 is pressed into soil layer, and pressure protect groove 6 will decompose this resistance, alleviate the power of bearing on 8 cylindrical outer walls of popping one's head in.

The center of probe 8 is provided with central blind hole 10, inner chamber 5 greater than central blind hole 10 is arranged in central blind hole 10 bottoms, be full of conductive liquid 4 in central blind hole 10 and the inner chamber 5, pressure transducer 2 seals in the conductive liquid 4 that is arranged in the central blind hole 10, central blind hole 10 upper port are provided with packoff 9, and sealing device 9 adopts sealing gasket to seal; Perhaps packoff 9 adopts the sealing gasket lid, no matter adopts the sort of structure must leave the lead outlet of pressure transducer 2.

The 8 middle part right cylinder outer walls of popping one's head in are provided with recess 11, and insulate conduction thin slice 3 sealing this recess 11 consistent with the cylinder physical dimension of probe 8 are had the conductive liquid 4 that is communicated with probe 8 central blind holes 10 in the recess 11 of insulate conduction thin slice 3 sealings.

Be communicated with by pipeline 12 between the conductive liquid 4 of the central blind hole 10 of described probe 8 and the conductive liquid 4 in the inner chamber 5 and insulate conduction thin slice 3 closed inner chambers.

The cable connection 1 of described pressure transducer 2 is from the pressure receiving converter 7 of the prior art that is connected probe 8 outsides after 8 the central blind hole 10 of popping one's head in is drawn, and this pressure receiving converter 7 is that pressure transducer 2 is sensed the device that the soil layer pressure signal converts voltage signal to by insulate conduction thin slice 3, conductive liquid 4.

Described insulate conduction thin slice 3 is weldingly fixed on the cylinder outer rim of probe 8, and its thickness is: 0.1mm-0.2mm.Select for use superhard and thin steel can better reflect soil layer pressure.

The central blind hole of described probe 8 seals with packoff 9, and sealing device 9 is sealing gasket or gland bonnet.

The invention provides the measuring method and the computing method of the probe of the above-mentioned in-situ real time measuring saturated fine soil borizontal stress of a kind of usefulness, described measuring method and computing method are to derive the horizontal consolidation coefficient C of probe 8 test place saturated fine grained soil layers by calculating according to the saturated fine grained soil horizontal stress of measuring _hWith Stationary side pressure coefficient K ₀, this theory and formula that calculates the derivation foundation is as follows:

1. according to the saturated fine grained soil consolidation theory, following formula is disclosed in materials such as disclosed section teaching:

T degree of consolidation U is constantly disclosed according to the saturated fine grained soil consolidation theory _t, time factor T _v, the stratum horizontal consolidation coefficient C _hComputing formula and soil mechanics principle of effective stress:

(1), degree of consolidation U _tComputing formula:

$U_t=\frac{u_0-u_t}{u_0}=1-\frac{u_t}{u_0}---\left(1\right)$

In the formula: U _t-t is the degree of consolidation at degree of depth place, stratum constantly;

u _t-t is degree of depth place, stratum excess pore water pressure constantly;

u ₀The initial excess pore water pressure in degree of depth place ,-stratum.

(2), time factor T _vComputing formula:

In the formula: the U-degree of consolidation;

T _v-time factor.

Utilize the curve fitting method, two formulas can be merged into following unified relational expression in the formula (2):

$U=\frac{{\left(\frac{4T_v}{\mathrm{\&pi;}}\right)}^{0.5}}{{(1+{\left(\frac{4T_v}{\mathrm{\&pi;}}\right)}^{2.8})}^{0.179}}---\left(3\right)$

Or represent T with U _v: $T_v=\frac{\frac{\mathrm{\&pi;}}{4}{U}^2}{{(1-U^{5.6})}^{0.357}}---\left(4\right)$

(3), horizontal consolidation coefficient C _hComputing formula:

$C_h=\frac{T_v{r}^2}{t}$ Or $T_v=\frac{C_{h}t}{r^2}---\left(5\right)$

In the formula: C _hThe horizontal consolidation coefficient on-stratum;

R-conehead bottom surface radius or permeable filter radius (meaning is the radius in expansion hole);

The t-excess pore water pressure reaches certain dissipation degree required time.

(4), soil mechanics principle of effective stress: σ=σ '+u _w

In the formula: the total stress of σ-soil layer

The effective stress of σ '-soil layer;

u _wThe pore water pressure of-soil layer (forming) by excess pore water pressure and hydrostatic force.

2. computing method

Because the increment of the effective stress that produces in the saturated fine grained soil layer after probe is pressed into is very little, therefore as if ignoring owing to probe is pressed into the effective stress increment of generation or the variation in time of effective stress increment that the supposition probe is pressed into generation, by the soil mechanics principle of effective stress as can be known, that the probe test is the t horizontal stress R at saturated fine grained soil layer test point place constantly _t,

R _t=σ '+u _t+ u, or u _t=R _t-σ '-u

The level of significance stress of σ ' in the formula-probe test place soil layer.

The hydrostatic force at u-test point place

If initial time horizontal stress R ₀, R then ₀=σ '+u ₀+ u, or u ₀=R ₀-σ '-u; Excess pore water pressure dissipates, and horizontal stress is R when finishing _f, R then _f=σ '+u.

So by formula (1), pop one's head in the constantly degree of consolidation U at MTD place of t _tFor:

$U_t=\frac{u_0-u_t}{u_0}=\frac{R_0-{\mathrm{\&sigma;}}^{\&prime;}-u-(R_t-{\mathrm{\&sigma;}}^{\&prime;}-u)}{R_0-{\mathrm{\&sigma;}}^{\&prime;}-u}=\frac{R_0-R_t}{R_0-R_f}---\left(6\right)$

Therefore formula (6) and probe 8 data of being derived by this method that test out can be derived the formula that calculates saturated fine grained soil horizontal consolidation coefficient in conjunction with formula (2), (4), (5).

Promptly utilize field test probe 8 to record the saturated fine grained soil horizontal stress R at degree of depth place and the relation curve (as Fig. 1) of time t, use 3 computing methods to calculate initial time R ₀, R when finishing dissipates _fThereby, obtain parameters such as the horizontal consolidation coefficient on saturated stratum and Stationary side pressure coefficient.

3. calculation procedure

(1) horizontal consolidation coefficient C _hCalculation procedure

1) according to the typical curve of probe 8 tests, chooses two t constantly in the beginning section of curve ₁And t ₂(degree of consolidation U＜60%), the stress of their correspondences are R ₁And R ₂, the degree of consolidation U then corresponding by formula (6) is respectively:

$U_1=\frac{R_0-R_1}{R_0-{\mathrm{<figure-callout\; id="2"\; label="R\; f\; U"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">R</figure-callout>}}_f}$ $U_{}$ ${}_2=\frac{R_0-R_2}{R_0-R_f}$

Can get by formula (5) and formula (2):

$T_{v1}=\frac{C_v{t}_1}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}=\frac{\mathrm{\&pi;}}{4}{\left(\frac{R_0-R_1}{R_0-R_f}\right)}^2$

${\mathrm{<figure-callout\; id="2"\; label="T\; v"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_v=\frac{C_v{t}_2}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}=\frac{\mathrm{\&pi;}}{4}{\left(\frac{R_0-R_2}{R_0-R_f}\right)}^2$

Above two formulas of simultaneous solution, can try to achieve:

$R_0=(R_1-R_2\sqrt{\frac{t_1}{t_2}})/(1-\sqrt{\frac{t_1}{t_2}})---\left(7\right)$

2) again at the back segment (degree of consolidation U＞60%) of trial curve, access time t ₃The time R ₃, can draw by formula (4):

$T_{v3}=\frac{C_v{t}_3}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}=\frac{\mathrm{\&pi;}}{4}{\left(\frac{R_0-R_3}{R_0-R_f}\right)}^2/{\left({1-\left(\frac{R_0-R_3}{R_0-R_f}\right)}^{5.6}\right)}^{0.357}$

According to T _V1, T _V2And T _V3Three formulas, can further try to achieve:

$R_f=R_0-\frac{R_0-R_3}{{(1-{((R_0-R_3)(\sqrt{t_2}-\sqrt{t_1})/(R_1-R_2)\sqrt{t_3})}^{5.6})}^{0.179}}---\left(8\right)$

3) calculate degree of consolidation U _t: utilize formula (6) to calculate pop one's head in the constantly degree of consolidation U at 8 MTD places of t _t

$U_t=\frac{u_0-u_t}{u_0}=\frac{R_0-{\mathrm{\&sigma;}}^{\&prime;}-u-(R_t-{\mathrm{\&sigma;}}^{\&prime;}-u)}{R_0-{\mathrm{\&sigma;}}^{\&prime;}-u}=\frac{R_0-R_t}{R_0-R_f}---\left(6\right)$

4) according to pop one's head in the constantly degree of consolidation U at 8 MTD places of t _tValue is by formula (2) or (4), can obtain t ₁, t ₂And t ₃The time time factor T _V1, T _V2And T _V3Numerical value

$T_v=\frac{\frac{\mathrm{\&pi;}}{4}{U}^2}{{(1-U^{5.6})}^{0.357}}---\left(4\right)$

5), can calculate horizontal consolidation coefficient C according to formula (5) _h:

$C_h=\frac{T_{v1}{r}^2}{t_1}=\frac{T_{v2}{r}^2}{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}=\frac{T_{v3}{r}^2}{t_3}---\left(5\right)$

(in the formula: r---probe (8) conehead bottom surface radius)

(2), calculate Stationary side pressure coefficient K ₀Step is as follows:

The Stationary side pressure coefficient K of soil ₀Be the level of soil to effective stress with vertically to the ratio of effective stress, ignore because probe is pressed into the effective stress increment of generation, the Stationary side pressure coefficient K of soil layer ₀For:

$K_0=\frac{R_f-u}{{\mathrm{\&sigma;}}_v-u}---\left(9\right)$

In the formula: the water pressure at u-test point place; U=r _wh

σ _v-test point place soil vertically to total stress; σ _v=∑ r _ih _i

r _wThe severe of-water;

The above height of water level of h-test point;

r _iThe severe of the above i layer soil of-test point;

h _iThe thickness of the above i layer soil of-test point.

Below, use of the present invention is described.

At first, with the present invention's tested soil layer of 8 conical end contact of popping one's head in, the screw thread head end of probe 8 connects external spiral depression bar, to pop one's head in by external spiral depression bar and 8 vertically to be pressed into when underground, saturated soil layer around the probe will produce pressure to probe, this pressure is by insulate conduction thin slice 3, conductive liquid 4 through the sealing water conservancy diversion, act on the pressure transducer 2, sensistor on the pressure transducer 2 is changed, through excess pressure receiving converter 7, this pressure receiving converter 7 is by insulate conduction thin slice 3 with pressure transducer 2, conductive liquid 4 is sensed the soil layer pressure signal and is converted electric signal to.Obtain the horizontal stress R at saturated soil layer depth place and the curve of time t relation after the process conversion; Calculate initial time horizontal stress R with 3 computing methods ₀Horizontal stress when dissipation is finished with excess pore water pressure; Calculate degree of consolidation U _tCalculated level coefficient of consolidation C _hWith the static side pressure COEFFICIENT K of calculating ₀Through aforementioned calculation, just can measure the saturated fine grained soil horizontal stress in position in real time.

Be exemplified below:

Select the scene, place to carry out the field test checking in the open air, the testing site lays respectively at underground 4.0m, 6.0m place.The about 1.0m of the bury of groundwater in this place, the stratum mainly is made up of silty clay and silt, and there is the muck soil interlayer part.Test result sees Table 1.

Table 1 soil layer stress ga(u)ge test result

Corresponding to the test point of degree of depth 4.0m, choose t arbitrarily ₁=5s R ₁=76kPa, t ₂=20s R ₂=72kPa, t ₃=2000s R ₃=60kPa 3 points can calculate according to formula (7), (8):

$\left\{\begin{array}{c}{R}_0=80\mathrm{kPa}\\ R_f=59.99\mathrm{kPa}\end{array}\right.$

According to R ₁, R ₂, R ₃, R ₀, R _fValue can calculate the degree of consolidation in these three moment, thereby can draw the time factor in these three moment by formula (4), (6):

$\left\{\begin{array}{c}{T}_{v1}=0.0314\\ {\mathrm{<figure-callout\; id="2"\; label="T\; v"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">T</figure-callout>}}_v=0.1285\\ T_{v3}=12.53\end{array}\right.$

The diameter 5.0cm of this probe can calculate the horizontal consolidation coefficient in these three moment respectively according to formula (5):

$\left\{\begin{array}{c}{C}_{h1}=0.039\mathrm{<figure-callout\; id="2"\; label="c\; m"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">c</figure-callout>}{m}^{}{}^2/\mathrm{<figure-callout\; id="2"\; label="s\; C\; h"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">s</figure-callout>}& \\ C_h{2}_{}=0.039\mathrm{<figure-callout\; id="2"\; label="c\; m"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">c</figure-callout>}{m}^{}{}^2/s\\ C_{h3}=0.039\mathrm{<figure-callout\; id="2"\; label="c\; m"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">c</figure-callout>}{m}^{}{}^2/s\end{array}\right.$

Because the underground water table 1.0m at this place, the water pressure that can calculate the test point place is 30kPa; The unit weight of supposing this stratum, place is 20kN/m ³, then the vertical pressure of this point is 80kPa.Can calculate the Stationary side pressure coefficient of this point according to formula (9):

K ₀＝0.62

In like manner, corresponding to the test point of degree of depth 6.0m, choose t arbitrarily ₁=5s R ₁=173kPa, t ₂=20s R ₂=168kPa, t ₃=3000s R ₃=111kPa 3 points can calculate:

$\left\{\begin{array}{c}{C}_{h1}=0.0054\mathrm{<figure-callout\; id="2"\; label="c\; m"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">c</figure-callout>}{m}^{}{}^2/\mathrm{<figure-callout\; id="2"\; label="s\; C\; h"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">s</figure-callout>}& \\ C_h{2}_{}=0.0054\mathrm{<figure-callout\; id="2"\; label="c\; m"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">c</figure-callout>}{m}^{}{}^2/s\\ C_{h3}=0.0054\mathrm{<figure-callout\; id="2"\; label="c\; m"\; filenames="C2005101222600015H1.png"\; state="\{\{state\}\}">c</figure-callout>}{m}^{}{}^2/s\end{array}\right.$

Equally can this Stationary side pressure coefficient:

K ₀＝0.86

Claims (7)

1. the probe of an in-situ real time measuring saturated fine soil borizontal stress, one end of this probe (8) is the thread head that is connected with external spiral depression bar, it is characterized in that: the other end of this probe (8) is for conical, and the middle part of probe (8) is for having the cylindrical of pressure protect groove (6); Be full of conductive liquid (4) in the central blind hole (10) of probe (8), pressure transducer (2) sealing is arranged in the interior conductive liquid (4) of central blind hole (10); Probe (8) middle part right cylinder outer wall is provided with recess (11), the insulate conduction thin slice (3) consistent with the cylinder physical dimension of probe (8) seals this recess (11), and the conductive liquid (4) that is communicated with probe (8) central blind hole (10) is arranged in the recess (11) of insulate conduction thin slice (3) sealing.

2. according to the probe described in the claim 1, it is characterized in that: be communicated with by pipeline (12) between the conductive liquid (4) in the central blind hole (10) of described probe (8) and the conductive liquid (4) of insulate conduction thin slice (3) closed inner chamber.

3. according to the probe described in the claim 1, it is characterized in that: the cable connection (1) of described pressure transducer (2) is connected on the outside pressure receiving converter (7) of probe (8) after the central blind hole (10) of probe (8) is drawn.

4. according to the probe described in the claim 1, it is characterized in that: described insulate conduction thin slice (3) is fixed on the cylinder outer rim of probe (8), and its thickness is: 0.1mm-0.2mm.

5. according to the probe described in the claim 1, it is characterized in that: the central blind hole of described probe (8) seals with packoff (9).

6. according to the probe described in the claim 5, it is characterized in that: described packoff (9) is a sealing gasket.

7. measuring method and computing method with the probe of in-situ real time measuring saturated fine soil borizontal stress described in the claim 1 is characterized in that: described measuring method and computing method are to derive the horizontal consolidation coefficient (C of probe (8) test place saturated fine grained soil layer by calculating according to the saturated fine grained soil horizontal stress of measuring _h) and static coefficient of horizontal pressure (K ₀), its measurement and calculation procedure are as follows:

(1), measurement and the calculated level coefficient of consolidation (C _h) step as follows:

1.. obtain the horizontal stress (R) at saturated fine grained soil layer MTD place and the curve of time (t) relation by measurement: be connected pressure receiving converter (7) with probe (8) and record the horizontal stress (R) at saturated fine grained soil layer MTD place and the curve of time (t) relation;

2. calculate initial time horizontal stress (R with 3 computing methods ₀) and the excess pore water pressure horizontal stress (R when finishing that dissipates _f), concrete calculation procedure is as follows:

A, on step horizontal stress (R) 1. and time (t) the relation curve section of beginning, choose two moment (t ₁, t ₂), the stress value of finding out their correspondences is respectively (R ₁, R ₂); Choose (t constantly at horizontal stress (R) and time (t) relation curve back segment ₃), find out the stress value (R of its correspondence ₃);

B, calculate initial time horizontal stress (R respectively with following formula (7) and (8) ₀) and the excess pore water pressure horizontal stress (R when finishing that dissipates _f) value:

$R_0=(R_1-R_2\sqrt{\frac{t_1}{t_2}})/(1-\sqrt{\frac{t_1}{t_2}})---\left(7\right)$

$R_f=R_0-\frac{R_0-R_3}{{(1-{((R_0-R_3)(\sqrt{t_2}-\sqrt{t_1})/(R_1-R_2)\sqrt{t_3})}^{5.6})}^{0.179}}---\left(8\right)$

3.. calculate the degree of consolidation (U _t): utilize formula (6) to calculate the pop one's head in the constantly degree of consolidation (U at (8) MTD place of t _t), formula (6) is as follows:

$U_t=\frac{u_0-u_t}{u_0}=\frac{R_0-{\mathrm{\&sigma;}}^{\&prime;}-u-(R_t-{\mathrm{\&sigma;}}^{\&prime;}-u)}{R_0-{\mathrm{\&sigma;}}^{\&prime;}-u}=\frac{R_0-R_t}{R_0-R_f}---\left(6\right)$

4.. the calculated level coefficient of consolidation (C _h):

A, according to the pop one's head in the constantly degree of consolidation (U at (8) MTD place of t _t) value, by following formula (2) or (4), obtain t ₁, t ₂, t ₃The time time factor T _V1, T _V2, T _V3Numerical value:

$T_v=\frac{\frac{\mathrm{\&pi;}}{4}{U}^2}{{(1-U^{5.6})}^{0.357}}---\left(4\right)$

B, calculate horizontal consolidation coefficient (C according to following formula (5) _h):

$C_h=\frac{T_{v1}{r}^2}{t_1}=\frac{T_{v2}{r}^2}{t_2}=\frac{T_{v3}{r}^2}{t_3}---\left(5\right)$

(in the formula: r---expression probe (8) conehead bottom surface radius)

(2), calculate static coefficient of horizontal pressure (K ₀) step is as follows:

Calculate Stationary side pressure coefficient (K according to following formula ₀)

$K_0=\frac{R_f-u}{{\mathrm{\&sigma;}}_v-u}---\left(9\right)$

In the formula: the hydrostatic force at u-test point place; U=r _wh

σ _v-test point place soil vertically to total stress; σ _v=∑ r _ih _i

r _wThe severe of-water;

The above height of water level of h-test point;

r _iThe severe of the above i layer soil of-test point;

h _iThe thickness of the above i layer soil of-test point.

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