Performance of a Large-Scale Excavation by Bottom-Up Technique in Hangzhou Soft Clay

This paper studied the excavation of a foundation pit above a running subway tunnel in Hangzhou soft soil. The zoned excavation and top-down construction techniques were adopted to control the deformation caused by foundation pit excavation. The excavation was divided into four parts, named Zone A, B, C, and D. Zone A adopted temporary diagonal bracing, and the control effect of deformation was poor; it was cancelled and changed to rapid excavation and thicker cushion in Zones B, C, and D. During the whole construction process, the lateral displacement and settlement of the diaphragm wall, surrounding ground surface, and building settlement were monitored and analysed. The data showed that the lateral displacement of the diaphragm wall was effectively reduced by the zoned excavation technique, and the maximum lateral displacement value of the diaphragm wall in Zone A was the least; rapid excavation and reduced soil exposure time also could effectively control the deformation, and the lateral displacement of the diaphragm wall in Zone C is less than Zone B and Zone D. The ground settlement is strongly related to the lateral displacement of the diaphragm wall. In order to reduce the surrounding ground and building settlements, efforts should be made to reduce the wall lateral displacement.

What to do when the results are insufficient: lessons from the excavation of a cairn field at Eikebakken, Øvre Øksnevad, Klepp

The cairn field at Eikebakken, Øvre Øksnevad, Klepp municipality, Rogaland, Norway, was excavated over the course of 26 weeks in the summer of 2016. The site had undergone an initial survey in 2008, indicating a total of 79 cairns. However, when the site was uncovered a total of 103 stone built structures were identified, as well as three separate settlement areas and evidence of prehistoric farming. The initial project plan and budget were written with the idea of focusing on a smaller number of more thoroughly excavated (i.e. single-context) cairns. The increased number of structures made this plan untenable. As the excavation progressed it also became clear that the single-context method was not returning the amount of data required. The excavation thus went through several major shifts in strategy in response to, primarily, the archaeology and the need to develop a representative data set, but also time/budgetary constraints and available labor resources. The strategy ultimately settled upon involved a much more rapid excavation of a larger number of cairns with a focus on the use of environmental evidence from the cairns, particularly material suitable for radiocarbon dating, but also a range of other methodologies, as a means of understanding the development of the cairn field. This article will discuss both the methodologies and prioritizations involved in the excavation and will present some brief, initial results.

Application of Bolter Miner Rapid Excavation Technology in Deep Underground Roadway in Inner Mongolia: A Case Study

Rapid excavation could mitigate the imbalance relationship between excavation speed and production needs that plays a pivotal role in the sustainable development of large underground coal mines. This paper provides a case study on Bolter Miner Rapid Excavation Technology (BMRET) in Menkeqing Coal Mine, which has a high production of 13 million tons per year in Inner Mongolia. The temporal characterization of excavation procedures is analyzed in detail based on field monitoring data. The improvement of the roadway driving process and efficiency under a new support design is introduced, and corresponding evaluation methods, including parallel operation index ( P x ) and unit drilling-hole index ( D x ), are proposed for BMRET. A field application is conducted to verify the effectiveness of the improved BMRET, which fully considers the structure characteristic of the bolter miner machine. The performance and reliability of this new support scheme are monitored in terms of roadway convergence and axial force of cable through professional instrumentation programs in the field. The results show that the average excavation speed of the BMRET is 36.15 m/day (1080 m/month), an increase of 99.72% compared with the original excavation technology, which indicates that the BMRET could provide high efficiency in roadway excavation and effectively control the stability of deep roadways. It is pivotal to apply BMRET to ensure sustainable and highly efficient coal production. This case study provides reference and guidance for rapid excavation of deep underground roadways with similar geological conditions.

Technology optimization on the rapid excavation in inclined shaft

Through a lot of investigation, many times of demonstrating scheme, the in-depth theoretic analysis, a large scale numeric simulation tests and the field tests, the operating line of the rapid excavation is equipped which are consisting of the way of the drilling and blasting, the bolt-mesh-spurting supporting and the trackless transportation. The key technology which includes the stable technology of controling the surrounding rock, the optimization technology of transportation system, the excavating technology of layered drilling and the technology of parallel and cross operation develops the integral management framework and the advanced technology framework with the operating line, which realizes the safe and efficient construction and provides rich experience for the similar mines.