Dependency conflicts in a project ??

If your projects share resources so much, then problems are inevitable. If you acquire more people, equipment and resources so each project has its own, you can reduce your risk of problems significantly. Since that’s the obvious answer, I assume it’s not an option.
You can also reduce the amount of problems and the cost of contingencies by operating fewer projects simultaneously. It’s not desirable, but given the severe resource dependencies you described it sounds like the best way to produce the most successful projects at the least cost.

Reduce the dependencies as much as possible , i have seen PM's allocate same resource in %, like 25% , 30%...etc in different projects , in practical this will not work and switching tasks cost more than waiting and also increase quality issues.

If the dependencies are inevitable close tracking and monitoring is the only way , should do risk management effectively and be proactive, should not wait problem/delay to happen to react/response should be able to predict and make changes to the plan to cover within contingency. if it goes above need to create exception plan

The question contains part of the answers. If several projects running concurrently are sharing the same resources, the risk of experiencing delays or budget overrun due to overtime increases. Thus, having less concurrent projects, or less interdependent, or increasing the workforce may be assessed to minimize risks.

At the end, it is about allocating time and effort to ensure a proper and thorough project control and monitoring.

Running many interrelated projects concurrently is in itself a risk. If it is deemed necessary to accept that risk, then what S. Rajasekar states is sensible, however, if there is a choice, then reduce that risk by running less concurrent projects.