Case:
Background information: A construction unit undertakes the construction of a mountain ridge heavy hill area expressway project, the starting and ending stations are K12 + 200 K27 + 700, and the design width of the roadbed is 245m, the schematic diagram of the longitudinal section design is shown in Figure 1-1, and the schematic diagram of the half-filled and half-excavated cross-section is shown in Figure 1-2. Among them, the K12+200 K15+600 section passes through the farmland, during which several farmland filling canals are passed, the average width of the canal is about 3m, and the bottom elevation of the silt at the bottom of the canal is about 1 lower than the average elevation of the soft soil of the farmland7m, the canal position is set up with a letter hole, and the culvert bottom treatment is in accordance with the design;Combined with geological conditions, the average thickness of the soft soil layer of farmland is 125m, the maximum depth is not more than 3m. Due to the low grade of local traffic roads, agricultural water fields, and dry land are precious, the contract stipulates that it is not allowed to borrow earthwork to fill the roadbed.
The following events occurred during construction:
Event 1: According to the raw materials of the whole road section and the thickness of the soft soil in the K12+200 K15+600 section, the construction unit adopts shallow treatment technology for the soft soil foundation.
Event 2: In the construction preparation stage, the construction unit checked the design documents and found that the total mileage of the subgrade fill in this contract section is about 350,000 m3, and the maximum fill height is 43M, mainly concentrated in K12+200 K15+600;The total amount of roadbed excavation is about 970,000 m3, mainly concentrated in K18 + 315 K21 + 035, and the excavation depth is 085m~15.7m, the mountain is hard limestone except for a small amount of weathered surface.
Event 3: After on-site investigation and consulting drawings, it was found that K20 + 223 K20 + 550 was a full-section excavation section, with a maximum vertical excavation depth of 58m, K20 + 50 K21 + 035 is half filled and half dug section, and the maximum digging depth is 157m3；In order to reduce land acquisition and maintain the stability of the roadbed, a more commonly used gravity retaining wall was designed in the semi-filled section, which mainly relied on the lateral thrust of the soil behind the wall to resist (a) of the altar wall.
Event 4: There are no obvious karst caves in the main crossing sections of the two tunnels, and the rocks are relatively hard limestone, and the rock mass is relatively broken, which belongs to the II L grade surrounding rock section. When the construction unit builds the rock-filled embankment, the fill road section is divided into four construction steps, respectively: below the roadbed surface (b) m is the first step, (b) m 15m is the second step, 15m (c) m is the first step, and (c) m and above is the fourth step.
Event 5: The construction unit used a vibrating roller with a self-weight of 15t when filling the roadbed of this project.
Question] 1 Explain the embankment filler of this project
2. Combined with the engineering background and considering the economics of the project, write down the two types of cushion and two shallow treatment methods suitable for the project in Event 1.
3. Write out two controlled blasting methods that are suitable for the rock characteristics of the excavated road section in Event 2. Combined with the requirements of the specification, this project.
How many levels of slope should be set up in the maximum excavation section
4 Answer the contents of A, B, and C in Event 3 and Event 4 respectively.
5 Correct the error in Event 5. First Class Constructor