Wenchuan Earthquake The Geology Problem and Engineering Solution Yuan Chen Shuopu Chen Wei Liang

Time: 12/05/ :28:04 Epicenter Location: Wenchuan, Sichuan °N °E Duration time: 80s Magnitude: 8.0 Richter scale Depth:19 kilometres Wenchuan Earthquake Source: earthquake-map/maps/earthquake-map-big.gif

Geology Reason for the Earthquake Deformation in Tibet as a result of the convergence between the Indian and the Eurasian Plates. The earthquake ruptured a reverse fault along the Longmen Shan Fold and Thrust Belt (LST).

Definition Liquefaction is a phenomenon wherein a mass of soil loses a large percentage of its shear resistance, where subjected to monotonic, cyclic, or shock loading, and flows in a manner resembling a liquid until the shear stresses acting on the mass are as low as the reduced shear resistance. Soil Liquefaction

Causes Flow liquefaction the undrained flow of a saturated, contractive soil when the static shear stress exceeds the residual strength of the soil. Cyclic softening cyclic shear due to pore pressure build-up in soils that would tend to dilate in undrained, monotonic shear. Soil Liquefaction

Common place Shallow, loose, saturated deposits of cohesionless soils Low-lying areas near bodies of water such as rivers, lakes, bays, and oceans. Soil Liquefaction

Reduce Liquefaction Hazards 1. Avoid liquefaction-prone areas 2. Soil mitigation 3. Structural mitigation.

1.Avoid liquefaction-prone areas Historical Criteria Geological Criteria Compositional Criteria State Criteria

2. Soil mitigation a. Vibro-compaction b. Vibro-replacement c. Deep dynamic compaction d. Compaction (pressure) grouting

3. Structural mitigation a. In Shallow foundation Aspects b. In Deep foundation Aspects

3. Structural mitigation a. In Shallow foundation Aspects All foundation elements in a shallow foundation must be tied together.

3. Structural mitigation b. In Deep foundation Aspects Piles must be connected to the cap in a ductile manner

Conclusion 1.Give basic description of Wenchuan Earthquake. 2.Find the geology problem from the earthquake. 3.Provide some engineering solutions to the earthquake.