CN101718876B - Method for monitoring stability and predicting destabilization of side slope based on change of state of strain of soil-rock mass - Google Patents

Abstract

The invention discloses a method for monitoring the stability and predicting the destabilization of a side slope based on the change of the state of strain of soil-rock mass, which is used for monitoring strain sensitivity and strain acceleration condition along a sensor distribution direction in the side slope to fulfill the aims of pre-warning and prediction under the condition that buried monitoring sensors do not change the stable state of the side slope by arranging a plurality of parallel or slightly inclined multi-point strain gauges or distributed strain gauges in a slope body of the side slope, judging the plastic zone and potential destabilization range of the side slope according to the strain sensitivity change of the multi-point strain gauges or the distributed strain gauges and evaluating the stability of the side slope. Specifically for the slope bodies which are not obviously deformed before the side slopes are destabilized, a conventional displacement monitoring method cannot monitor and pre-warn the destabilization. Compared with the conventional method, the method has inimitable advantages, and compared with the conventional method for monitoring the stability of the side slope and a landslide disaster, is more direct and more rational monitoring means.

Description

A kind of slope stability monitoring and unstability Forecasting Methodology based on the sudden change of rock soil mass strain regime

Technical field

The present invention relates to engineering geology Disaster Study fields such as slope stability monitoring and landslide prediction, especially relate to a kind of slope stability monitoring and unstability Forecasting Methodology based on the sudden change of rock soil mass strain regime, this method can satisfy the needs of slope project monitoring and unstability prediction.

Background technology

The factor that influences slope stability is a lot, and natural generally speaking side slope often is in steady state (SS), but because its primary stress field distribution has been broken in effects such as later stage surrounding enviroment transition, mankind's activity, thereby the steady state (SS) of side slope is changed.Generally, the generation of sliding mass all can be accompanied by obvious displacement, adopts surface displacement to monitor to judge the stability of side slope and landslide prediction comparatively reasonable to this type of side slope unstability and sliding process.But by the landslide example statistical study of a large amount of engineerings, before nearly side slope unstability more than 30%, but do not follow obvious distortion sign, in other words, adopt conventional displacement monitoring to have the regular hour lag-effect to this type of side slope, can't satisfy the purpose of modern project monitoring and early warning prediction.

The monitoring content that adopts in the slope project mainly comprises at present:

(1) works status monitoring: comprise the stress of ruggedized constructions such as pile body, anchoring body, the monitoring of displacement state, the works of monitoring all belongs to the structures of reinforcing side slope, monitoring result only is the duty of structure, can't set up definite getting in touch with side slope slope body stability;

(2) domatic displacement: domatic displacement monitoring to unstability before side slope to produce the sloping body of moderate finite deformation comparatively effective, can judge the tendency toward sliding of side slope according to the Changing Pattern of displacement monitoring, but can't obtain significant monitoring result to the less side slope of distortion before the unstability, simultaneously, domatic displacement monitoring point is subjected to the influence (as falling rocks etc.) of various external factors easily, causes bigger monitoring error or invalid monitoring;

(3) sloping body intrinsic displacement: generally adopt multipoint displacement meter to monitor, its monitoring result is the same with domatic displacement, can't effectively monitor the less side slope body of distortion before the unstability, and monitoring result also may produce than mistake owing to the influence of external factor simultaneously.

Simultaneously, discover: it mainly is because the change of slope ground body inside regional area stress-strain state produces that slope sliding produces displacement, adopt displacement monitoring just to judge reason by the presentation result, relate to an inverting and time Delay Process, obtaining of Monitoring Data is difficult to satisfy engineering prediction needs.

The side slope unstability is mainly caused by following reason:

(1) load: make due to the external loads that the side slope sliding force increases;

(2) underground water and vibrations: make the mutagenic external factor of slope ground body stress state;

(3) rock soil mass parameter change: various unfavorable factors cause the rock soil mass physical and mechanical parameter to produce the change that is unfavorable for stability of slope;

(4) local or whole inefficacy of original ruggedized construction: for the tall and big side slope of the industries such as artificial side slope, especially water power of having reinforced, as time goes by, the influence of reasons such as weathering, corrosion causes the local of existing ruggedized construction or all inefficacies.

With the above change that influences the factor of slope stability, unified Definition is the change of generalized load, and promptly generalized load increases, and is unfavorable for stability of slope, otherwise then helps stability of slope.

For realizing targets such as the real-time unstability prediction of side slope, judgement sliding mass scope, especially at the less side slope body of distortion before the unstability, the pace of change of utilization monitoring side slope slope body internal strain state (stress state) and variation acceleration, being applicable to the change of the inner rock soil mass stress-strain state of timely discovery side slope information, is a kind of more direct, essential and rational monitoring means.

Summary of the invention

The present invention is just in order to solve the deficiency of traditional monitoring method, adopt the strain sensitivity of a certain direction in multiple spot strainometer or the distributed strain flowmeter sensor monitoring side slope, judge the stability of side slope and determine the potential unstability scope of side slope according to the Changing Pattern of strain sensitivity.

The present invention seeks to realize by following proposal:

A kind of slope stability monitoring and unstability Forecasting Methodology based on the sudden change of rock soil mass strain regime are made up of sensor device that comprises a plurality of strain monitoring points and data acquisition system (DAS), and the strain in the side slope body is monitored.The multiple spot strain-gage pickup is embedded in the side slope body, because itself rigidity is less, very little to the steady state (SS) influence of side slope, data acquisition system (DAS) is arranged at multiple spot strain transducer end on the side slope face.

This programme is based on the plasto-elasticity principle, the Changing Pattern of analysis of slope rock soil mass strain regime.The behavioral characteristics sensitivity definition of side slope is the rate of change of certain physics parameter behavioral characteristics amount, when rock soil mass in the side slope enters the plastic stage by elastic stage, the strain sensitivity of respective nodes is undergone mutation in multiple spot strainometer or the distributed strain flowmeter sensor, by data collection and analysis, thereby reach the purpose of judging the slope and land slide scope and assessing its degree of stability.The monitoring strain sensitivity is more more timely and effective than conventional displacement monitoring, reflect the change information of slope ground body stress strain regime more accurately, provides scientific guidance to the reinforcing choose opportunities of instable slope.

In embodiment, provided two concrete theoretical derivations:

In conjunction with inference one, can monitor the position of the inner plastic zone of side slope, promptly possible sliding surface position.By inference one as can be known, in generalized load increase process, any zone enters the plastic stage by elastic stage, and its strain sensitivity will obviously increase.

In conjunction with inference two, can judge the steady state (SS) of sloping body.After the side slope part enters the plastic stage, if generalized load continue to increase, then the pace of change of strain sensitivity will sharply increase and cause the generation of side slope unstability.

The strain variation monitoring method is compared its advantage and is shown with classic method:

(1) with regard to external manifestation, the change of the inner microstrain state of sloping body is always prior to domatic displacement, and especially for rock mass slope, obviously be better than the displacement criterion with the actual measurement strain as main criterion this moment.

(2) mensuration of the particularly sloping body internal strain of actual measurement strain state change helps determining of position of slip surface, and then definite sliding mass volume, grasps the landslide scale, and it has crucial meaning to the prediction on landslide and the understanding of the extent of injury thereof.

(3) test of sloping body internal strain state is not subjected to the influence of external environment conditions such as domatic falling rocks substantially, all tests superior (internal displacement monitoring generally also is to measure as reference system with domatic) than internal displacement at aspects such as accuracy and convenience.

(4) layout of internal strain monitoring point is not subjected to the influence of the current deformation state of side slope, even certain displacement has taken place side slope, still can carry out the laying of strain monitoring point under this state.

Description of drawings

The geometric configuration of Fig. 1 side slope and monitoring equipment are arranged sketch;

Fig. 2 example side slope geometric parameter and multiple spot strainometer are arranged sketch;

Following No. 1 multiple spot strainometer of Fig. 3 slope soil different moisture content condition or distributed strain meter strain sensitivity be the distribution situation calculating chart along its length;

Following No. 2 multiple spot strainometers of Fig. 4 slope soil different moisture content condition or distributed strain meter strain sensitivity be the distribution situation calculating chart along its length;

Following No. 3 multiple spot strainometers of Fig. 5 slope soil different moisture content condition or distributed strain meter strain sensitivity be the distribution situation calculating chart along its length;

Following No. 4 multiple spot strainometers of Fig. 6 slope soil different moisture content condition or distributed strain meter strain sensitivity be the distribution situation calculating chart along its length;

Following No. 5 multiple spot strainometers of Fig. 7 slope soil different moisture content condition or distributed strain meter strain sensitivity be the distribution situation calculating chart along its length;

The inner plastic zone of body, Fig. 8 slope expander graphs;

The strain sensitivity of Fig. 9 multiple spot strainometer or distributed strain meter peak point is with the change curve of water cut;

Figure 10 multiple spot strainometer or distributed strain meter peak point answer the change curve of fluctuating acceleration with water cut.

Embodiment

Below in conjunction with accompanying drawing, slope stability monitoring and the unstability Forecasting Methodology based on the sudden change of rock soil mass strain regime of the present invention is elaborated.

Fig. 1 is that the geometric configuration and the monitoring equipment of side slope arranged sketch, 3. 2. this monitoring system be made up of with data acquisition system (DAS) multiple spot strainometer or distributed strain meter, the side slope slope 1. interior strain variation speed of body is monitored, 2. described multiple spot strainometer or distributed strain meter comprise a plurality of strain monitoring points, and the result of monitoring gained multiply by result behind the amplification coefficient for the section monitoring point along the strain of multiple spot strainometer or distributed strain meter cloth set direction.

By theoretical derivation, 1. in the generalized load loading procedure, any zone enters the plastic stage by elastic stage to the discovery side slope, and its strain variation speed is that strain sensitivity will obviously increase; In side slope after 1. the part enters the plastic stage, if generalized load continues to increase, then strain sensitivity will sharply increase and cause the generation of side slope unstability.

Therefore, can adopt multiple spot strainometer or distributed strain meter 2. to monitor the 1. strain sensitivity of interior a certain direction of side slope, judge side slope plastic zone 1. and potential unstability scope according to strain sensitivity and variation acceleration thereof, the stability of assessment side slope.

(1) basic theories

The strain increment that is produced under unit generalized load incremental contribution is called strain sensitivity

The strain sensitivity of elastic stage is designated as Strain sensitivity after the surrender stage is designated as

Postulate according to Drucker and can get following inference:

Inference one: stabilizing material rate of straining under the ratio loading environment satisfies along any direction α:

${\stackrel{\·}{\mathrm{\ϵ}}}_{\mathrm{\α}}^y\≥{\stackrel{\·}{\mathrm{\ϵ}}}_{\mathrm{\α}}^e---\left(1\right)$

Proof: for the loading procedure under the ratio load condition, stress satisfies

σ _ijdσ _ij＞0 (2)

Following formula shows that the symbol of stress and stress increment is identical.Therefore, be without loss of generality, below suppose σ in the proof procedure _Ij＞0.For σ _IjThe method of proof of＜0 situation is identical.

Adopt the reduction to absurdity proof as follows:

In the space arbitrarily the stress and strain of any can adopt principle stress and principal strain to be described.Be without loss of generality, prove above-mentioned in the principal stress space below.

Owing to be that ratio loads, therefore, in deformation process, remain fixing constant rate between each components of strain.Be that each principle stress satisfies:

dσ ₁∶dσ ₂∶dσ ₃＝1∶B ₂∶B ₃ (3)

dε ₁∶dε ₂∶dε ₃＝1∶C ₂∶C ₃ (4)

If the direction cosine of any direction α and three principal axis of stress are respectively l, m, n.Then

dσ _α＝dσ ₁l ²+dσ ₂m ²+dσ ₃n ²＝dσ ₁(l ²+B ₂m ²+B ₃n ²) (5)

dε _α＝dε ₁l ²+dε ₂m ²+dε ₃n ²＝dε ₁(l ²+C ₂m ²+C ₃n ²)＝kdε ₁ (6)

If exist in the loading procedure

$\frac{d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^y}{d{\mathrm{\&sigma;}}_{\mathrm{\&alpha;}}}<\frac{d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^e}{d{\mathrm{\&sigma;}}_{\mathrm{\&alpha;}}}---\left(7\right)$

Because d σ _α＞0

Therefore, $d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^p=d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^y-d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^e<0---\left(8\right)$

Then $d{\mathrm{\&sigma;}}_{\mathrm{\&alpha;}}d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^p<0---\left(9\right)$

For stabilizing material, postulate as can be known by Drucker:

$d{\mathrm{\&sigma;}}_{\mathrm{\&alpha;}}d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^p\&GreaterEqual;0---\left(10\right)$

Formula (9) and formula (10) contradiction, therefore, formula (7) is false.Therefore, certainly exist

$\frac{d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^y}{d{\mathrm{\&sigma;}}_{\mathrm{\&alpha;}}}\&GreaterEqual;\frac{d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^e}{d{\mathrm{\&sigma;}}_{\mathrm{\&alpha;}}}---\left(11\right)$

Card is finished.

Inference two: after entering the surrender stage, to answer fluctuating acceleration be monotonically increasing function to stabilizing material under the ratio loading environment

${\stackrel{\&CenterDot;\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}^y\&GreaterEqual;0---\left(12\right)$

Proof: because ε ^y=ε ^p+ ε ^e

D ε ^eWith d σ be linear relationship, ${\stackrel{\&CenterDot;\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}^e=0,$ Therefore, inference two is equivalent to

${\stackrel{\&CenterDot;\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}^p\&GreaterEqual;0---\left(13\right)$

Adopt reduction to absurdity.

After supposing material yield, exist

${\stackrel{\&CenterDot;\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}^p=-\mathrm{\&xi;}<0---\left(14\right)$

Then ${\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}^p=-\mathrm{\&xi;\&sigma;}+\mathrm{\&eta;}---\left(15\right)$

ξ and η are integration constant in the formula.For the ratio load condition, these two constants can carry out integration in conjunction with starting condition and constitutive model.Generally ξ and η are the function of σ, in a certain definite moment, can suppose that ξ and η are constant, are used to find the solution

Approximate solution, that is:

${\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}^p=-\frac{\mathrm{\&xi;}}{2}{\mathrm{\&sigma;}}^2+\mathrm{\&eta;\&sigma;}+\mathrm{\&gamma;}=-\frac{\mathrm{\&xi;}}{2}{(\mathrm{\&sigma;}-\frac{\mathrm{\&eta;}}{\mathrm{\&xi;}})}^2+\frac{2\mathrm{\&xi;\&gamma;}+{\mathrm{\&eta;}}^2}{2\mathrm{\&xi;}}---\left(16\right)$

Because ξ＞0, therefore,, always there is σ for η and ξ arbitrarily _N, as σ＞σ _NThe time, ${\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}^p<0.$

This shows works as ${\mathrm{\&sigma;}}^y>{\mathrm{\&sigma;}}_N^y$ After, for stress increment d σ arbitrarily ^y＞0, d ε ^p＜0, then

$d{\mathrm{\&sigma;}}_{\mathrm{\&alpha;}}d{\mathrm{\&epsiv;}}_{\mathrm{\&alpha;}}^p<0---\left(17\right)$

Formula (17) is postulated with Drucker and is contradicted, so formula (14) is false, promptly

${\stackrel{\&CenterDot;\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}^y\&GreaterEqual;0$

Card is finished.

Because the factor that influence slope stability is a lot, so the generalized load of this paper can be any disturbance that may cause the slope stability variation, for example: the inefficacy of domatic load, water cut, former reinforcing anchor pole, the creep of rock soil mass etc.

Judge the unstability scope of side slope and assess the stability of side slope according to strain sensitivity.In conjunction with two inferences, detailed applications is as follows:

Inference one can be used for monitoring the position of the inner plastic zone of side slope, promptly possible sliding surface position.By inference one as can be known, in generalized load increase process, any zone enters the plastic stage by elastic stage, and its strain sensitivity will be undergone mutation.

Inference two is used to judge the steady state (SS) on landslide.After the side slope part enters the plastic stage, if generalized load continue to increase, then the pace of change of strain sensitivity will sharply increase and cause the side slope unstability.

(2) theoretical calculating is verified

For the checking above-mentioned theory correctness and set forth its application in the slope monitoring process.Below with soil body water cut be changed to the example influence of slope stability is analyzed:

For an even soil-slope, the geometric parameter of side slope as shown in Figure 2.Wherein, side slope height 1. is 9000mm, and the toe degree of depth is 4500mm.5 multiple spot strainometers or distributed strain meter be arranged successively in parallel from side slope toe 1. to the top 2., be respectively the multiple spot strainometer 1～No. 5.

The elastic modulus of the soil body is 10MPa, and Poisson ratio is 0.25, and dry density is 1.353g/cm ³The yield criteria of the soil body satisfies the Mohr-Coulomb criterion.The cohesive strength and the angle of internal friction of the soil body change along with the variation of water cut, and the variation relation of cohesive strength and angle of internal friction and water cut can be expressed as

1gc＝-c _aW+c _b，1gφ＝-φ _aW+φ _b (18)

In the formula, c is the cohesive strength (kPa) of soil; φ is angle of internal friction (degree); W is a water cut.Parameter is taken as in the formula: c _a=3.6232; c _b=23344; φ _a=4.5975; φ _b=2.0134;

Aforesaid generalized load represents to cause arbitrarily the factor of slope stability variation.The stability of this sample calculation analysis side slope changes characteristics with the stress and strain of side slope inside in the variation of water cut and the research change of moisture content process.

5 horizontal multiple spot strainometers for this reason installing in side slope are provided with 120 monitoring nodes in each strainometer, the laying of strainometer does not change the steady state (SS) of side slope.Therefore in computation process, suppose that the elastic modulus of multiple spot strainometer and the soil phase are same, diameter is the material of 1mm, and bonds fully with the soil body.

The result of multiple spot strainometer monitoring gained is strain, because strain numerical value is very little, is data processing and graphic presentation convenience, and logarithm value multiply by an amplification coefficient according to actual needs.Strain sensitivity is unified for multiply by 7.85 result of calculation in below calculating.

Along with the increase of water cut, the cohesive strength of side slope reduces, angle of internal friction reduces, and density increases simultaneously, and these all are unfavorable for the stable of side slope.In the process that water cut increases, the part soil body progressively enters the plastic zone in the side slope, and the soil body can be reflected by the strain variation in the multiple spot strainometer by the process that elasticity enters plasticity.The strain sensitivity of each node such as Fig. 3 in the multiple spot strainometer～shown in Figure 7.As seen from the figure, strain sensitivity increases very big in regional area, and most zone remains unchanged.In conjunction with the theory of inference one as can be known, material enters mecystasis from elastic stage, and strain sensitivity will take place significantly to increase.The zone that strain sensitivity remains unchanged is the elastic region, and the zone that strain sensitivity is undergone mutation is plastic zone (determination methods of strain sensitivity sudden change is determined by formula 22).Node with strain sensitivity sudden change is the boundary, and the strain sensitivity catastrophe point of 5 multiple spot strainometers is coupled together, and can obtain the plasticity expander graphs of side slope, as shown in Figure 8.Fig. 8 shows that the plastic zone scope of side slope progressively enlarges with the increase of water cut, and the plastic zone is at first in toe formation, then progressively to the development of top, slope.If the plastic zone is pushed up perforation from the end, slope to the slope, the expression side slope enters plastic limit.For this example W=0.248 situation, the plastic zone is near connecting, and at this moment, side slope is near ultimate limit state.Adopt the strength degradation method that the side slope of W=0.248 situation is carried out stability analysis, the safety coefficient of side slope is 1.02, and near 1, this shows the correctness that this paper analyzes.

Utilize strain sensitivity can judge the position of slipping plane,, can adopt the rate of change of strain sensitivity promptly to answer fluctuating acceleration to judge for judging the stability of slope sexual state.Fig. 9 and Figure 10 are respectively the strain sensitivity of multiple spot strainometer peak point and answer the change curve of fluctuating acceleration with water cut.As seen from the figure: (1) when the soil body was in elastic stage, strain sensitivity was a constant substantially, answered fluctuating acceleration trend and zero; (2) enter the plastic stage by elastic stage when the soil body, strain sensitivity increases with the increase of generalized load, and this theory with inference one conforms to; (3) perforation is pushed up in the plastic zone from the toe to the slope before, the strain sensitivity of plastic zone and answer fluctuating acceleration to increase with the increase of generalized load, this theory with inference two conforms to.But answer fluctuating acceleration to be essentially the steady-state growth state, in case the plastic zone is when connecting, the acceleration of all multiple spot strainometers all changes rapid increase into by progressively increasing, and promptly the value of acceleration is undergone mutation, and can judge that side slope has been in critical conditions this moment.

According to above-mentioned analytic process, utilize the monitoring result of multiple spot strainometer or distributed strain meter, judge that the stability of slope sexual state is divided into following three steps:

(1) analyze the situation of change of each multiple spot strainometer strain sensitivity, according to the multiple spot strainometer the formation order of position, corresponding side slope plastic zone, the plastic zone of judging side slope is to push up development from the toe to the slope, still pushes up the toe development from the slope.If development is pushed up in the plastic zone from the toe to the slope, the monitoring result of selective analysis top multiple spot strainometer then is if toe development, the then monitoring result of selective analysis bottom multiple spot strainometer are pushed up in the plastic zone from the slope.Push up from the toe to the slope with the plastic zone below and develop into the judgment criterion that example illustrates slope stability;

(2) mean value and the variance of calculating top multiple spot strainometer strain sensitivity.Promptly

$\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_i---\left(19\right)$

$S_{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}^2=\frac{1}{n-1}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{({\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_i-\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}})}^2---\left(20\right)$

N is a monitoring node number in the multiple spot strainometer in the formula.

Suppose that strain sensitivity is normal distribution, so,

Degree of confidence be that the forecast interval of 1-α is

$(\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}}-S_{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}{u}_{1-\mathrm{\&alpha;}/2},\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}}+S_{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}{u}_{1-\mathrm{\&alpha;}/2})---\left(21\right)$

U in the formula _1-α/2The expression degree of confidence is the bilateral fractile of 1-α.

For the application of this method, common desirable α=0.05, then u _1-α/2=1.96.Therefore, if the strain sensitivity of the interior arbitrfary point of multiple spot taseometer

Satisfy following formula:

${\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_i>\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}}+1.96S_{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}---\left(22\right)$

Then can have 95% confidence level to judge that the strain sensitivity of this monitoring point undergos mutation, the soil body enters the plastic stage.

(3) after the top pairing soil body of multiple spot strainometer enters the plastic stage, calculate the position of strain sensitivity peak value, promptly

${\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_j=\underset{i=1~n}{\max }\left({\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_i\right)---\left(\text{23}\right)$

Calculate the fluctuating acceleration of answering of peak point.Before peak point enters plasticity, measured m constantly, these accelerometers constantly are shown

(i=1,2 ..., m), the acceleration that enters behind the plastic zone is designated as

The average and the variance of m acceleration before finding the solution:

${\stackrel{\stackrel{\&OverBar;}{\&CenterDot;\&CenterDot;}}{\mathrm{\&epsiv;}}}_j=\frac{1}{m}\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}{\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}_j^i---\left(24\right)$

$S_{{\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}_{\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009102373299E00032.png"\; state="\{\{state\}\}">j</figure-callout>}}}^2=\frac{1}{m-1}\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}{({\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}_j^i-{\stackrel{\stackrel{\&OverBar;}{\&CenterDot;\&CenterDot;}}{\mathrm{\&epsiv;}}}_j)}^2---\left(25\right)$

Suppose that answering fluctuating acceleration is normal distribution, adopt the analytical approach identical with strain sensitivity, when setting up in the time of instantly, can judge that m+1 answers fluctuating acceleration to undergo mutation constantly, at this moment, side slope enters critical conditions.

${\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}_j^{m+1}>{\stackrel{\stackrel{\&OverBar;}{\&CenterDot;\&CenterDot;}}{\mathrm{\&epsiv;}}}_j+1.96S_{{\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}_j}---\left(26\right)$

In this example, by the strain sensitivity analysis as can be known, the strainometer that enters plasticity is at last counted in No. 5 multiple spot strains.In each operating mode of calculating, when soil body water cut W=0.246, the average and the standard deviation of No. 5 multiple spot strainometer strain sensitivities are respectively:

$\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}}=0.873,$ $S_{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}=0.236$

And the multiple spot strainometer in all strain sensitivity values all less than $\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}}+1.96S_{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}=1.336,$ Therefore can judge that this moment, multiple spot strainometer The corresponding area was in elastic stage.

When soil body water cut W=0.248, the average and the standard deviation of strain sensitivity are respectively:

$\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}}=1.594,$ $S_{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}=1.007$

Then $\stackrel{\stackrel{\&OverBar;}{\&CenterDot;}}{\mathrm{\&epsiv;}}+1.96S_{\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}=3.568$

By more as can be known, the zone of 37≤i in the multiple spot strainometer≤47, ${\stackrel{\&CenterDot;}{\mathrm{\&epsiv;}}}_i>3.568,$

This shows that this moment, the strain sensitivity of multiple spot strainometer was undergone mutation, and the soil body enters plasticity.

Because No. 5 multiple spot strainometers are positioned at side slope top, utilize the stability of answering fluctuating acceleration to judge side slope below:

When soil body water cut W=0.248, the position of No. 5 multiple spot strainometer strain sensitivity peak values is

Therefore study the fluctuating acceleration of answering of this point.The average of answering fluctuating acceleration and the variance of peak point are in soil body water cut 0.238≤W≤0.246 scope:

${\stackrel{\stackrel{\&OverBar;}{\&CenterDot;\&CenterDot;}}{\mathrm{\&epsiv;}}}_{41}=183.186$

$S_{{\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}_{41}}=179.260$

The fluctuating acceleration of answering when soil body water cut W=0.248 is:

${\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}_{41}^{0.248}=3472.4>{\stackrel{\stackrel{\&OverBar;}{\&CenterDot;\&CenterDot;}}{\mathrm{\&epsiv;}}}_{41}+1.96S_{{\stackrel{\&CenterDot;\&CenterDot;}{\mathrm{\&epsiv;}}}_{41}}=534.536$

Can judge that thus the fluctuating acceleration of answering of side slope undergos mutation, thereby can judge that side slope enters critical conditions.

According to said method and process, realized accurate monitoring stability of slope situation, grasped the potential slope sliding face position and the purpose of sliding mass volume.

Claims (2)

1. the slope stability based on the sudden change of rock soil mass strain regime is monitored and the unstability Forecasting Methodology, it is characterized in that:

(1) the strain variation state to the inner multiple spot of side slope slope body carries out the monitoring of strain sensitivity variable quantity, pace of change and variation acceleration;

(2) when strain sensitivity is constant, judge that the slope ground body deformability is in elastic stage, when strain sensitivity is undergone mutation, judge that the slope ground body deformability enters the plastic stage by elastic stage;

(3) when strain sensitivity is the steady-state growth state, the judgement plastic zone is pushed up from the toe to the slope as yet and is connected fully, when the strain sensitivity of all multiple spot strainometers or distributed strain meter is all undergone mutation, can judge the plastic zone near connecting, side slope has been in the critical conditions of unstability;

It is under the condition that does not change the current steady state (SS) of side slope that described strain variation state to the inner multiple spot of side slope slope body is monitored, the body inside, side slope slope that will monitor, install many levels or slow multiple spot strainometer or the distributed strain meter that inclines, in described every multiple spot strainometer or the distributed strain meter a plurality of axial strain monitoring nodes are set, can monitor the strained situation of arbitrary node along its length;

The end that is positioned on the side slope surface at described multiple spot strainometer or distributed strain meter is provided with data acquisition system (DAS).

2. slope stability monitoring and unstability Forecasting Methodology based on the sudden change of rock soil mass strain regime according to claim 1, it is characterized in that: the described condition that does not change the current steady state (SS) of side slope comprises makes described multiple spot strainometer or distributed strain meter integral rigidity and slope ground body deform in same pace.

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