Developmental Mechanism of Rainfall-Induced Ground Fissures in the Kenya Rift Valley
Abstract
:1. Introduction
2. Tectonic Geological Background
2.1. Formation of the Kenya Rift Valley
2.2. Plate Movement and Tectonic Stress Field
2.3. Basement Structure
- The Kenya rift is a typical active continental rift. Deep thermal dynamic activity has formed a regional tectonic environment for the extension of the rift area, which is conducive to the formation of tension cracks in rock and soil.
- The Kenya Rift Valley is the separation boundary between the Victoria Plate and the Somali Plate, with the latter moving southeast away from the former.
- The direction of the minimum horizontal stress in the Kenya rift rotated 45° clockwise from near E-W to NW-SE, which is its current trend. This stress environment is conducive to the formation of NE-SW tensile fractures.
- The major changes in the direction and structural evolution of the Kenya rift are controlled by the Cambrian basement NW-SE tectonic zone of weakness, and the formation of ruptures in the buried rock and soil in the rift area may also be affected by this shear zone.
3. Materials and Methods
3.1. Investigation and Analytical Methods Used to Determine Ground Fissure Characteristics
3.2. Analysis of the Ground Fissure Formation Mechanism
3.3. Numerical Simulation Method of Rainfall Infiltration
4. Results
4.1. Plane Distribution Characteristics of Ground Fissures
4.2. Profile Structure Characteristics of Ground Fissures
4.3. Fracture Characteristics of Concealed Bedrock
4.4. Numerical Simulation of Rainfall Infiltration Process
4.5. Deformation Characteristics under Rainfall Infiltration
5. Discussion
5.1. Genesis Mechanism of Concealed Bedrock Fracture
5.2. Relationship between Rainfall Infiltration and Ground Fissures
6. Conclusions
Author Contributions
Funding
Conflicts of Interest
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Saturation | 0.02 | 0.18 | 0.25 | 0.36 | 0.50 | 0.66 | 0.80 | 0.89 | 0.94 | 0.97 | 1.00 |
---|---|---|---|---|---|---|---|---|---|---|---|
Matrix suction | −100 | −61.58 | −37.93 | −23.36 | −14.38 | −8.86 | −5.46 | −3.36 | −2.07 | −1.27 | 0 |
Soil Sample Number | Sampling Depth (m) | Water Content (%) | Density (g/cm3) | Grain Specific Gravity | Void Ratio | Internal Friction Angle (°) | Cohesion (kPa) |
---|---|---|---|---|---|---|---|
#1 | 0.5 | 24.28 | 1.41 | 2.62 | 1.31 | 27 | 17 |
#2 | 2.5 | 22.31 | 1.44 | 2.63 | 1.23 | 32 | 14 |
#3 | 3.5 | 23.2 | 1.46 | 2.61 | 1.20 | 34 | 15 |
#4 | 4.5 | 16.4 | 1.36 | 2.65 | 1.27 | 35 | 15 |
#5 | 6 | 30.1 | 1.48 | 2.60 | 1.29 | 29 | 16 |
Average value | - | 23.3 | 1.43 | 2.62 | 1.26 | 31.4 | 15.4 |
Soil | Dry Density (g/cm3) | Void Ratio | Internal Friction Angle (°) | Cohesion (kPa) | Young’s Modulus (MPa) | Poisson Ratio | Permeability Coefficient (m/h) | Surface Pore Flow Velocity (m/h) |
---|---|---|---|---|---|---|---|---|
Silty sand | 1.2 | 1.3 | 30 | 15 | 16 | 0.3 | 2.88 × 10−2 | 2.8 × 10−2 |
Strike Interval | Quantity | Average Strike | Strike Interval | Quantity | Average Strike |
---|---|---|---|---|---|
0–10° | 5 | 1 | 270–280° | - | - |
10–20° | 1 | 17 | 280–290° | - | - |
20–30° | 3 | 24.08 | 290–300° | - | - |
30–40° | 1 | 38 | 300–310° | - | - |
40–50° | - | - | 310–320° | - | - |
50–60° | - | - | 320–330° | 2 | 323.05 |
60–70° | - | - | 330–340° | 2 | 336.3 |
70–80° | - | - | 340–350° | 3 | 343.0 |
80–90° | - | - | 350–360° | 1 | 353.4 |
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Liu, Y.; Peng, J.; Wang, F.; Zhu, F.; Jia, Z.; He, M. Developmental Mechanism of Rainfall-Induced Ground Fissures in the Kenya Rift Valley. Water 2022, 14, 3215. https://doi.org/10.3390/w14203215
Liu Y, Peng J, Wang F, Zhu F, Jia Z, He M. Developmental Mechanism of Rainfall-Induced Ground Fissures in the Kenya Rift Valley. Water. 2022; 14(20):3215. https://doi.org/10.3390/w14203215
Chicago/Turabian StyleLiu, Yang, Jianbing Peng, Feiyong Wang, Fengji Zhu, Zhijie Jia, and Ming He. 2022. "Developmental Mechanism of Rainfall-Induced Ground Fissures in the Kenya Rift Valley" Water 14, no. 20: 3215. https://doi.org/10.3390/w14203215