Monitoring of slope engineering

Slope engineering includes:

The slope of reservoir area;

The dam foundation slope;

Highway and railway slope;

The slope of the side of the tunnel;

The slope of the foundation pit;

River bank revetment slope;

Natural slope.

The purpose and characteristics of slope monitoring

The main purpose of slope monitoring is:

To realize the information design and construction of the old slope regulation or the new slope construction.

To judge the sliding, sliding range and development trend of the slope.

The effect of the slope regulation is tested.

For the study of landslide theory and slope design method, the data are accumulated.

Characteristics of slope engineering monitoring:

The monitoring area is large and the properties of the rock and soil are complex.

The slope of the slope is gradually formed, and the position of some monitoring points should be changed accordingly.

The duration of monitoring is long, which runs through the whole construction process.

Content and method of slope engineering monitoring

1. geodetic method

Measurement of two-dimensional horizontal displacement: forward intersection (two or three directions);

Bilateral distance rendezvous.

The horizontal displacement measured in one direction: collimation method;

Small angle method;

Distance measurement.

Vertical displacement measurement: geometric leveling method;

Precision trigonometric leveling method.

Advantages: a wide range of monitoring surfaces can be used to determine the surface deformation range of the slope.

The range is not limited;

The absolute displacement of the slope can be observed.

Disadvantages: affected by terrain visibility conditions and meteorological conditions;

The workload is large and the working cycle is ten.

The ability of continuous observation is poor.

2.GPS (Global Positioning System) measurement method

Features of GPS: the positioning accuracy can reach millimeter level

Advantages: the observation point between no visibility, convenient location;

The observation is not limited by the weather conditions and can be observed all weather.

The three-dimensional coordinates and velocity of the observation point can be measured at the same time.

When the range is more than 10km, the precision is better than the photoelectric range finder.

Shortcoming: the price is expensive.

Purpose: slope monitoring of complex terrain conditions, large fluctuations or buildings and poor visibility.

3. close range photogrammetry

Advantages: Photography (periodic repetitive photography) is convenient, foreign industry time and labor saving;

The space position of many observation points can be obtained at the same time.

Shortcomings: low precision.

Application: the slide body is monitored in the stage of rapid change and upheaval.

The rock cliff cracks in the airport;

The monitoring of the change rate of the surface displacement of the landslide is large.

Three. Instrument observation method

Features: the monitoring content is rich, the precision is high, the measuring range is adjustable, and the instrument is easy to carry.

The damage to the testing instrument can be avoided by the bad environment.

The data are intuitionistic and reliable, and can be observed continuously.

The selection and arrangement of the ground

Production of monitoring points

Measurement implementation

Summary of data and the formation of reports

2. underground displacement monitoring and sliding surface measurement

- Drilling

Element embedment and initial measurement

Measurement implementation

Summary of data and the formation of reports

3. environmental factors monitoring

Long term observation of groundwater level

Precipitation statistics

Others, such as the turbid degree of ground temperature and groundwater and the change and flow of chemical components, etc.

Sound wave test

Vibration test

Implementation of other tests

Two. Summary and analysis of monitoring data

1. reports of monitoring

Monitoring daily reports;

Phase statement;

Monitoring summary table

2. related drawings

The time history curve of each monitoring project;

The rate time curve of each monitoring project;

Vectorgraph and contour line of surface displacement and deformation;

Image map of various monitoring projects in different working conditions and special dates

3. Analysis Report

The following contents should be included in the general analysis report:

Engineering geological background

Progress in construction and Engineering

Monitoring purposes, monitoring project design and workload distribution

Monitoring cycle and frequency

Summary of all information

The judgment and conclusion of the curve

Numerical calculation and analysis

Conclusions and recommendations

1. Control benchmarks:

Plane control network line (four wire) 17km; three equal height control network line 21.69km; four level network line 12.4km.

The horizontal angle with J3 type theodolite 6 measuring determination; vertical angle measurement is 2 determined by J2 type theodolite wire method; elevation control network level is measured by DS3 double level, level ruler and observation.

2, the layout of the ground deformation displacement monitoring point

The northwest wedge: 7 point (G22-G28); the eastern tectonic mud belt d3:21 point G1 G21); around the site: 5 points (G29 G33).

3. Data processing and results analysis of ground deformation displacement monitoring

The horizontal displacement vector measured at each time is plotted on the plane with the point as the origin. The average direction of each monitoring point is 25 times as the horizontal displacement total direction of the point. The projection of displacement vector on the horizontal displacement general direction is the total horizontal displacement of the point.

Criteria for determining horizontal displacement:

The values measured at each time have a tendency in a clear direction, and the maximum offset is more than 2cm.

Criteria for determining vertical displacement:

The absolute value of the maximum vertical displacement is greater than 1cm in the 25 monitoring points. The positive or negative displacement is systematic, or the difference between the first and last displacement is obvious after regression calculation.

7 points on the ground of the wedge-shaped geological structure in the Northwest:

The horizontal displacement occurred at 2 points:

22.7mm (SW8 ~ 49 ');

The 22.5MM (SE43 ~ 21 ').

There are 5 points that have vertical displacement:

-15.3 ~ -22.5mm (NE17 degrees to 21 degrees 30 '11');

The -31.4mm (SE43 degrees to 21 ');

(3) -13.4 ~ -37.7mm (vertical subsidence).

In the 21 points of the D3 upper plate of the eastern tectonic mud belt:

The horizontal displacement occurred at 7 points:

The 23.5 ~ 52.0mm (NE27 degrees to 85 degrees 39 '09');

The 22.2 ~ 56.0mm (SE35 degrees to 51 degrees 42 '34').

There are 8 points that have vertical displacement:

-10.8 ~ -76.2mm (NE18 degrees to 85 degrees 46 '09');

(2) -25.0 ~ -51.0mm (vertical subsidence).

Underground deformation monitoring

1. The layout and monitoring of the underground deformation monitoring hole:

There are 20 underground deformation monitoring holes in the D3 upper rock mass of the pinch belt.

The inclinometer uses SX a 20 type of inclinometer:

The wedge-shaped geological structures in the Northwest: DX-1 to DX-3, DX-7 and DX-8;

The original landslides in the eastern hillside: DX-6, DX-11 to DX-14 and DX-20;

The top of the hillside: DX-9, DX-10.

The sliding micrometer monitoring using sliding micrometer swiss:

The eastern slope platform: H4, H15, H16, H18

The small deformation of the rock mass of the D3 upper plate near the main plant site was measured.

The 6 point bar extensometer is used for monitoring the multi point extensometer.

The eastern slope slope site: D5, D17, Mei D19

2. Results and analysis of underground deformation monitoring

Monitoring time: 2 years, monitoring frequency: average 1 times per month.

In the northwest wedge-shaped geological structure, the horizontal displacement is 4.50mm to 24.84mm;

The eastern slope near the main building site is 2.5m ~ 5.0m in depth is very little;

In the eastern slope eyebrow structure, the mud belt is near D3, and the hole D5 is deep in the 28.0m, and the 10.2mm is sinking.

The original landslide margin is west, 8 to 11.8M deep in the hole D17 and D19, and sink 0.8mm and 2.2mm;

On the original landslides in the eastern hillside, it is equivalent to the structure of the tectonic mud belt D3.

The horizontal displacement: 7.55mm ~ 19.50mm (5 6 measuring holes in);

The direction of slope, the maximum displacement occurs at a depth of 8.0mm ~ 25.0mm.

Five, displacement monitoring results and stability evaluation

Stability assessment of 1. wedge-shaped geological structures:

The displacement of most of the measured points is slow as time goes on.

The wedge - shaped geological structure has a small, slow and slow displacement, which will continue.

The creep of the weak structural surface at the bottom of the wedge-shaped geological structure is the main cause of the displacement of the rock mass.

2. stability assessment of Eastern hillside

The eastern slope: the ground measuring point G19 and G21 are not displaced;

The 4 sliding micrometer, measured displacement only + 1.55 ~ -2.70mm;

2 multipoint extensometer, the settlement was only 0.8mm and 2.2mm.

Conclusion: the eastern slope structure with mud with D3 on stability.

The eastern slope: 12 of the 21 ground displacement monitoring points have been displaced obviously.

Horizontal displacement: 22.2 ~ 56.0mm, direction to the slope;

Settlement: 10.8mm ~ 76.2mm.

Multipoint extensometer D5: Settlement: 10.2mm, depth position: 28.0m;

6 in addition to the DX - 11 inclinometer are significant horizontal displacement:

The horizontal displacement is 7.55 to 19.5mm, but the displacement has gradually slowed down.

Conclusion: the rock mass within the perimeter of the eastern slope of the slope is still moving slowly down to the slope.

The bottom boundary of rock mass deformation is still near the structure of D3.

The main reason is the creep of the rock mass near D3.