Assessing slope protection methods for weak rock slopes

Assessing slope protection methods for weak rock slopes in Southwestern Taiwan Engineering Geology 91 (2007) 100– 116 Der-Her, Yi-En Yang , Hung-Ming Lin 指導教授：段錦浩 教授 組別：第三組 7101042020 黃雅各 7101042032 張勝堤

Introduction This paper presents the results of field study involving the collection of geological data along the South-2 (S-2) Freeway in the southwestern region of Taiwan detailing the effectiveness of existing slope protections. 2

Characteristics of mudstone in Southwestern Taiwan Distribution of mudstone in Southwestern Taiwan 3

Characteristics of mudstone in Southwestern Taiwan Slaking and swelling characteristics of the mudstone 4

Erosion, vegetation and slope protection Vegetation on mudstone slopes Since the mudstone is loosely cemented, and is subjected to weathering with water, exfoliation interfaces may cause immediate slaking and loss of mudstone surfaces, which leads to further runoff erosion and exposure of plant roots. 5

Erosion, vegetation and slope protection Existing mudstone slope protection methods 6

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Slope protection methods employed in S-2 Freeway 7

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Slope protection methods employed in S-2 Freeway 8

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Slope failure modes Along the S-2 Freeway to the south of Meishan, slope failures occurred mainly in the form of surface erosion, shallow slides and side ditch cracks. 9

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Slope failure modes 10

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Slope failure modes 11

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Slope failure modes 12

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Slope failure modes 13

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Distribution of slope failure modes by protection methods 14

Field investigation of mudstone slope problems along South-2 (S-2) Freeway Distribution of slope failure modes by rock types 15

Attributes of slope failures and possible remedial measures Water and drainage 16

Attributes of slope failures and possible remedial measures Water and drainage 17

Attributes of slope failures and possible remedial measures Vegetation on weak rock slopes 18

Attributes of slope failures and possible remedial measures Slope angles and slope height 19

Attributes of slope failures and possible remedial measures Requirements for effective slope protection methods A slope protection method must be able to resist erosion, prevent fine-grained soil loss, and facilitate adequate drainage. A surface water drainage system is required to effectively control the rainwater. The slope protection facilities must have adequate strength to resist the swelling pressure of the mudstone. The slope protection facilities must increase slope stability and facilitate vegetation growth. 20

Soil-Tire–Vegetation Method 21

Soil-Tire–Vegetation Method 22

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Soil-Tire–Vegetation Method C 1 B 1 D 1 E 1 A 1 F 1 G 2 B 2 C 2 D 2 E 2 F 2 2004/12/12 48

Soil-Tire–Vegetation Method 2005/02/27 49

Soil-Tire–Vegetation Method 2005/04/02 50

Soil-Tire–Vegetation Method 2005/06/26 51

Soil-Tire–Vegetation Method 2005/10/16 52

Soil-Tire–Vegetation Method 2006/03/21 53

Soil-Tire–Vegetation Method 2006/06/06 54

Soil-Tire–Vegetation Method 2006/08/30 55

Soil-Tire–Vegetation Method 2006/12/07 56

Soil-Tire–Vegetation Method 2007/02/10 57

Soil-Tire–Vegetation Method 58

Concluding remarks The ability to resist erosion, fine-grained soil loss prevention, proper surface water drainage systems to control stormwater runoff. The ability to resist the swelling pressure of the mudstone. Proper features to increase the stability of the slope and facilitate vegetation growth. 59

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