# Application of Flow Velocity and Direction Measurement System in Slope Stability Analysis

^{1}

^{2}

^{3}

^{4}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Overview of the Case Landslide

#### 2.1. Regional Geological Condition

^{4}m

^{3}, and the volume of the soil with creep deformation at the front edge was about 15 × 10

^{4}m

^{3}. A landslide is a translational landslide in which the surface soil slides along the bedrock surface. The overall landslide area presents the characteristics of being high in the south while being low in the west. The azimuth of the sliding direction is about 220°. The leading-edge elevation is about 440 m. The trailing edge elevation is about 560 m, and the maximum elevation difference is 120 m. The plan view of the landslide area is shown in Figure 2.

^{−8}m/s). The color of this layer is grayish yellow, and the content of breccia is about 5%. The grain size of the gravel is 0.2–2 cm, and the rest is cohesive soil. The number of hammers in the cone dynamic penetration test is 5–9 per 10 cm, with a relatively mixed and uniform composition. The middle layer is silty clay with breccia. The breccia may be related to the nearby faults, but detailed geological surveys do not find any fault activity that affects the stability of the slope. The trailing edge is very thick, while the leading edge is not. The permeability is good (k = 4.85 × 10

^{−6}m/s), and the particle size is between 2 cm and 15 cm. The color is gray to gray yellow, the particle size distribution is poor, and the change is large. The content of gravel is 50–75%. Some boreholes contain boulders, the diameter of which is 20–40 cm. The parent rock of the gravel is tuff. It is easy for it to collapse and fall off. The lower layer is the underlying bedrock, of which the surface is strongly weathered or fully weathered, and the main components are tuff and muddy siltstone. The color is gray to gray black, and the structure is silty, layered, tuffaceous, or block and relatively complete. The landslide area has been affected by faults in history, and more fractures were developed, but there has been no active fault since the Quaternary.

#### 2.2. Failure Characteristics of the Case Landslide

## 3. Materials and Methods

#### 3.1. Measuring Principle of the FVDS

#### 3.2. Improved Bishop Method Considering Hydrodynamic Pressure

_{i}is the hydrodynamic pressure on the strip, and the direction of the pressure is down along the bottom of the strip. Then the vertical force balance equation of the soil strip is as follows:

_{i}and m for l

_{i}.

#### 3.3. Estimation of Hydrodynamic Pressure Based on ANNs

_{i}is the hydrodynamic pressure of the groundwater in the i-th soil strip, v is the flow velocity of the groundwater, k is the permeability coefficient of the soil at the measurement location, and γ

_{w}is the gravity of the water.

_{1}, x

_{2}, …, x

_{m})

^{T}and the corresponding output is Y = (y

_{1}, y

_{2}, …, y

_{k})

^{T}. The dimension of the input vector is m, the dimension of the output vector is k, and the number of samples is n. The GRNN could adjust the network structure according to the training samples automatically. In addition, the number of nodes need not be determined by the users. The transfer function of the i-th neuron in the model layer is:

## 4. Result

## 5. Discussion

## 6. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

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**Figure 5.**The deformation and failure characteristics of the Fanshantou landslide. (

**a**): Collapse in the front of the landslide; (

**b**): Cracks in the front of the landslide; (

**c**): Cracks in the north side of the landslide; (

**d**): New cracks in the north side of the landslide; (

**e**): Cracks of buildings in the middle of the landslide.

**Figure 6.**Composition and probe structure of the flow velocity and direction system (FVDS). (

**a**) Photo of the FVDS in use on-site. (

**b**) Composition of the FVDS. (

**c**) Probe structure of the FVDS.

Soil | $\mathsf{\gamma}$/kN ·m^{−3} | c/kPa | φ |
---|---|---|---|

Gravel with clay | 18.19 | 12.5 | 12.5° |

Silty clay with breccia | 18.66 | 3 | 24.5° |

Strongly weathered bedrock | 19.30 | 22 | 16.0° |

Drainage Conditions | No Consideration of Groundwater | Traditional Bishop Method | Improved Bishop Method |
---|---|---|---|

Before drainage | 1.443 | 1.129 | 1.009 |

After drainage | 1.443 | 1.389 | 1.321 |

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**MDPI and ACS Style**

Ge, Q.; Zhang, J.; Chen, Z.; Li, J.
Application of Flow Velocity and Direction Measurement System in Slope Stability Analysis. *Water* **2021**, *13*, 700.
https://doi.org/10.3390/w13050700

**AMA Style**

Ge Q, Zhang J, Chen Z, Li J.
Application of Flow Velocity and Direction Measurement System in Slope Stability Analysis. *Water*. 2021; 13(5):700.
https://doi.org/10.3390/w13050700

**Chicago/Turabian Style**

Ge, Qi, Jingjing Zhang, Zhongxuan Chen, and Jin Li.
2021. "Application of Flow Velocity and Direction Measurement System in Slope Stability Analysis" *Water* 13, no. 5: 700.
https://doi.org/10.3390/w13050700