DISCUSSION AND RECOMMENDATIONS. It is understood that the existing structure will be replaced with a two-span timber, steel pile supported structure; and that grades will be raised by approximately 1.0 m. It is anticipated that the existing structure will be removed, and the bridge replaced in the same location, maintaining a similar open channel below. The following discussion provides geotechnical recommendations to support design and construction. APPROACH FILLS It appears that the existing fills were placed on the natural channel bottom. The underlying material comprises a very loose to loose silty sand with trace to frequent organics, and frequent wood was encountered throughout. It is likely that the existing embankment was constructed to near the maximum achievable height at the time of the original bridge construction. Observations on site also indicate that the existing gabion structures have deformed, which may be attributed to settlement of the underlying materials. Raising grades will require widening of the existing approach embankments to maintain the current road width. Embankments should be constructed no steeper than 2 horizontal to 1 vertical and be constructed of select borrow materials. Stability analyses were conducted for both drained and undrained analyses, assuming the marine deposits under the existing embankment are normally consolidated with the height of fill above them. Outside of the footprint of the existing embankment, the marine deposits were assumed to be normally consolidated. If any soft or organic materials are present adjacent to the existing embankments, they should be removed from beneath the base of the widened embankment footprint, down to the silty sand deposit encountered in the investigation. If the existing gabion structures are to be used to support increasing site grades, internal and global stability analyses should be carried out to assess the gabion’s serviceability. Preliminary estimates indicate that settlements in the order of 10 to 20 cm under the center of the existing embankment will be generated from the fill placement, with the potential for larger settlements occurring under the widened embankment slopes. Based on the composition of the underlying materials it is anticipated that primary settlements would occur throughout the construction period. Secondary or creep settlements of the embankment are estimated to be 1 to 2 cm per log-cycle of time. PILE FOUNDATIONS Steel H-piles driven to refusal in bedrock are a practical option ...
DISCUSSION AND RECOMMENDATIONS. The data analysis is discussed in this chapter in the context of the theoretical framework with the aim of answering the four research questions laid out in the chapter 1.2.2. First, each research question is discussed separately, then the study is evaluated regarding the achieved results, validity and reliability. Finally, recommendations for possible ways to improve the compatibility and credibility of the EGA initiative are presented.
DISCUSSION AND RECOMMENDATIONS. Overview The following is understood based on the information provided: • the existing corrugated steel culvert (1,200 mm diameter) is to be replaced with an 1,800 mm diameter High Density Polyethylene (HDPE) highway culvert located along the same alignment as the existing culvert; • an overflow pipe, comprised of a 1,200 mm diameter (HDPE) highway culvert, is to be installed 3 m c/c south of the proposed 1,800 mm culvert (1.5 m clear span between the two pipes); • the inlet and outlet of the 1,800 mm culvert are to be set at el. 1.64 m and el. 1.53 m, respectively; • the inlet and outlet of the 1,200 mm culvert are to be set at el. 2.25 m and el. 1.48 m, respectively; • the pipe bedding is to consist of a 450 mm layer of Class A gravel; and • no changes to the final road grade are planned. The subsurface conditions encountered at the site may generally be summarized as 3.4 to 4.3 m of compact to loose fill materials, over a 760 mm layer of loose topsoil (encountered at BH-04 only), over a compact to dense glacial till stratum and sandstone bedrock. The effect of these conditions on the design and installation of the replacement culvert(s) are considered in the following sections.
DISCUSSION AND RECOMMENDATIONS. It is understood that the proposed replacement bridge is to be located in the same location as the existing structure. The existing abutments will be removed, and the existing fills pulled back in order to increase the hydraulic opening of the channel. The new structure will span approximately 9 m between abutments. Based on the findings of the present investigation, the surface of the native glacial till layer varies from 1.2 to 2.0 m below the water level. As such it is anticipated that for ease of construction a pile supported structure will be the preferred option for the bridge replacement. However, it may prove economical to support the structure on spread footings placed on native glacial till or structural fill placed over the till, and as such geotechnical design recommendations for both types of foundations are provided.
DISCUSSION AND RECOMMENDATIONS. It is understood that the proposed structure will likely either consist of a prefabricated arch or a clear span bridge. The subsurface conditions encountered near the proposed structure alignment (i.e., at BH-02) may generally be summarized as 3.5 m of very loose marine silt/sand that directly overlies a compact glacial till stratum and sandstone bedrock, at a depth of 6.6 m. The river is tidally influenced with an OHWM located near the ground surface level of the mudflats. Both spread footing and pile-supported foundations could be considered for use at the site based on the conditions encountered as discussed in the following sections. Spread Footing Foundations Spread footing foundations could be considered for use at the site provided that issues associated with excavation below the groundwater table and through the very loose mudflat soils can be addressed. It is recommended that the groundwater table be temporarily lowered to facilitate excavation to the till surface. Control of groundwater inflow may require a temporary river diversion and will likely require pumping from a sump(s) located below the required depth of excavation. Although lowering of the groundwater table prior to footing excavation should improve the stability of the excavation side slopes, flatter cut inclinations than the typical 1 horizontal to 1 vertical may still be necessary to achieve stable conditions. If it is preferable to limit the horizontal extent of the excavation, consideration could be given to some means of temporary shoring such as sheet piling. A large modified trench box could also be considered to assist with the safe placement of foundations and to limit the size of the excavation footprint. Precast footings placed on a granular base may also be beneficial to permit timely backfilling and to limit the time that the excavation must remain open. Any soft or disturbed soils should be removed from the bearing surface prior to footing placement. If softening persists, consideration could be given to over-excavating the bearing surface (e.g., by 300 mm) to allow the placement of clean granular layer such as concrete stone or Class D gravel. The granular layer would help stabilize the bearing surface and should assist in groundwater control. Spread footings placed on undisturbed till, or a granular layer placed over the till, may be designed using an allowable bearing pressure of 150 kPa. Associated total and differential settlements should be less than 25 mm and 15 m...
DISCUSSION AND RECOMMENDATIONS. It is understood that the proposed structure will likely consist of a four-span bridge. Based on the subsurface conditions encountered, spread footing foundations, pile-supported foundations, or some combination thereof, could be considered for use at the abutment and pier locations. Since similar subsurface conditions were encountered during the present investigation as compared to those encountered during the initial investigation, the recommendations pertaining to the design of spread footing and pile- supported foundations provided in our initial report are still applicable (refer to previous in the Appendix). Some additional comments and recommendations pertaining to spread footing foundations are provided below. Spread Footing Foundations As recommended previously, spread footings placed on undisturbed till, or on a granular layer placed over the till, may be designed using an allowable bearing pressure of 150 kPa. Associated total and differential settlements would be less than 25 mm and 15 mm, respectively. In the event that higher capacities are required, consideration could be given to founding directly on the bedrock surface, depending on the depth of excavation required. The depth of excavation below the groundwater table may also be a limiting factor. At BH-06, located near the proposed west abutment, sandstone bedrock was encountered at a depth of 5.4 m below ground surface. At BH-05, located near the proposed east abutment, sandstone bedrock was encountered at a depth of 8.2 m below ground surface, and approximately 2.4 m below the groundwater table. Although the sandstone bedrock surface should not be susceptible to water disturbance, the temporary lowering of the groundwater table may be required at some locations to facilitate excavation to the bedrock surface and concrete/footing placement. Spread footing foundations placed directly on the sandstone bedrock surface, or on a granular levelling course placed directly over the bedrock surface, may be designed for an allowable bearing pressure of up to 400 kPa. Associated total and differential settlements would be less than 25 mm and 15 mm, respectively. The granularly levelling course, if required, could consist of a well-compacted 150 to 300 mm layer of clean crushed stone such as concrete stone or Class D gravel. The granular layer would also assist in groundwater control where necessary. We would be pleased to provide further geotechnical design input for this project on an as-required,...
DISCUSSION AND RECOMMENDATIONS. Harbourside understands from the Department that the new structure will be a buried HDPE pipe or buried precast concrete box culvert approximately 27 to 28 m in length supported directly on Class 'A' gravel (approximately 400 to 450 mm thick). The underside of gravel will bear on glacial till with an approximate elevation of 18.1 m at the outlet (downstream) and approximate elevation of 18.5 m at the inlet (upstream). The alignment of the new structure will be in the area of BH01 and BH04. CULVERT BASE Base preparation for culvert installation should consist of removal of all asphalt, fill, loose sands and any other deleterious materials (peat, organics, etc.) down to native undisturbed glacial till. The Class A should be placed in lifts suitable for the compaction equipment being used and compacted to 100 percent standard Xxxxxxx maximum dry density (SPMDD). It would be prudent to minimize the duration the glacial till subbase is exposed prior to placing the gravel. Prolonged exposure may lead to subbase (till) softening. Any soil that becomes excessively disturbed as a result of construction activity or softened due to water infiltration should be removed from the bearing surface prior to gravel placement. If softening persists, consideration could be given to the over-excavation of the bearing surface to allow for the placement of clean gravel or rockfill layer. Excavations within the existing fills and underlying silty sands should be no steeper than 1 horizontal to 1 vertical without means of shoring. Slopes that extend below the water table will likely require further flattening or the use of a blanket of well graded rockfill to provide stability from sloughing. Groundwater should be kept to a minimum in the excavations to prevent disturbance of the glacial till which is susceptible to softening. Xxxxxxxxxx could be accomplished by sloping the base of the excavation and, pumping from the low end if required. The Class A gravel base overlying the glacial till under the full height embankment (>4 m) would have a bearing resistance at Ultimate Limit States (ULS) of at least 350 kPa. A bearing resistance of 250 kPa can be used for design of the culvert under the embankment side slopes provided it has a minimum effective width of 0.5 m and a burial depth (culvert height plus Class A gravel thickness) layer of at least 1.5 m. The ULS bearing resistance includes a resistance factor of 0.5 in accordance with CAN/CSA S6-14. The total settlement of the culvert...
DISCUSSION AND RECOMMENDATIONS. This evaluation highlighted the impact of the KAFP on the career and professional development of alumni, as perceived by alumni themselves and KAFP staff. Overall, the program was perceived to contribute significantly to LIST: change in employment status, increased scientific productivity post graduation, and tailored services during their training at RSPH. Qualitative Results Perception of challenges and opportunities faced by the KAFP. One of the perceived challenges of staff members that the KAFP currently faces is the lack of public health practice in Saudi Arabia. The field is relatively new, with no history of public health practice. May trained professionals in the health field are mainly in medicine, and have no formal training in public health. Older professionals who have decision-making powers about career trajectories in public health have been trained in various forms of medicine but not in public health. This adds a strain to the development of the public health workforce once the graduates go back to serve in their country. Due to the lack of knowledge of the field, their degree is not recognized the same way other advanced degrees are recognized, so the system of incentives such as promotion tracks and salary raises are not there for those who decide to pursue public health. This causes an obstacle for public health in general and the program, as it limits and discourages students from joining. Another challenge faced by trainees is the lack of strong language and analytical/quantitative skills compared to their student counterparts at RSPH. Most of the Fellows who have joined the program come from medical backgrounds, and their medical education system is structured in such a way that does not reinforce analytical, statistical and critical thinking skills. This presents a challenge when selecting the department of their choice, as well as adjusting to the rigorous courses which require analytical and quantitative skills. For example, students interested in joining the Epidemiology and Biostatistics departments have admission challenges due to weak quantitative skills. With the additional academic support of the program, the fellows went through a steep learning curve but were able to circumvent these challenges. In addition to the analytical/quantitative challenges, trainees also face the barrier of English language skills. This is understandable given that it is their second language. The key challenge in this area is the immediate adjust...
DISCUSSION AND RECOMMENDATIONS. This section draws together the key discussions and recommendations made by the workshop. These recommendations will be forwarded to the IWC Scientific and Conservation Committees and ACCOBAMS Parties.
DISCUSSION AND RECOMMENDATIONS. XXX’s involvement in this project dates back to its initiation, but during Part Two they decided to reduce their direct involvement in construction-related VIPs. Nonetheless, the results of the work performed under this project are still valid and can provide a foundation for pursuing the further development of residential-construction VIP applications. Representatives of Xxxxxx have indicated that the firm intends to bring its VIP product to the United States market and they seem interested in pursuing construction-related uses. The company’s representative in the United States has expressed an interest in visiting the Research Center to discuss our work, and we have discussed their product with multiple attic stair producers. Additionally, product concepts, based on our understanding of the Xxxxxx VIPs, have been developed and circulated to industry members. The preliminary indications are positive. One firm has requested a product sample and costing data. Two other firms have asked how to contact Xxxxxx. DOW will not actively develop this market in the near term, but they have indicated that technical developments in this field can be handled through its network of fabricators, who manufacture finished VIPs and design systems for using them. One possibility is that building component producers could work directly with members of the network using development agreements. DOW’s network of VIP fabricators includes the following companies: • Advantek Incorporated • Energy Storage Technologies • SAES USA • Thermal Visions Incorporated While the product concepts have drawn interest, considerable work remains if new applications are to reach the market. This work will need to proceed at a pace that accommodates the requirements of all firms involved. New products often involve new technologies, new markets and new obstacles that firms need to research and understand thoroughly since substantial funds can be at stake. Adjustments and readjustment of product designs can require the participation of both component and application producers, so effective communication between the firms will be vital. The work under this project represents an important contribution to the state of knowledge about VIP applications for residential construction. The research has explored the potential for thermal performance gains, anticipated costs of attic hatch and stair applications, regulatory barriers, existing industry attitudes and market potential. Much of the uncertainty reg...
